DIGITAL MEDIA SERIES: RHINOCEROS

TUTORIAL BOOK OF RHINOCEROS FOR STUDENTS AND PROFESSIONALS

RHINOCEROS D

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JINMO RHEE, EDDY MAN KIM

School of Architecture

Chapter 10. V-Ray

Chapter 10.

V-RayÂŽ

This chapter shows only the essential features of V-Ray that can not only be easily learned but also enrich the architectural design process. This chapter will handle V-Ray as a tool to quickly visualize designer’s ideas and test spatial design. For advanced users who wish to learn more about V-Ray beyond the scope of this chapter, it is recommended to read and practice the official manual and tutorial videos on the Chaos Group (developer) website.

While it may seem that the best way to create good renderings depends on the rendering engine’s settings, high quality model is the ultimate key to success. Therefore, it is important for the user to pre-establish the necessary libraries and settings to be easily accessed, so that the user can focus more time on building a high quality model. In this effort, this chapter will provide basic understanding of the V-Ray software and sample scene files for users to easily set up their own rendering environment.

The V-Ray used in this chapter is based on V-Ray for Rhinoceros 6, 3.60.02.

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Bezier Curve B-Spline Nurbs

Grasshopper

VB

Background

Scripting based Modeling

C#

Object Point Knot Control Point (CP) Difference of Knot and CP Use Points CP-modeling

NURBS

Point Curve Overall Organization Panels Toolbar Snap Controls

Python

Command System Command Structure Shortcut Sync With Autocad Tips for Setting shortcuts Compatibility (dwg export/import)

Mesh Boolean Reduce Mesh Weaver Bird

Plug-in Based Types of plug-in NURBS Mesh, Solid, NURBS Benefits of Using Rhino

Mesh Edit

Type of Curve Line and Polyline Polygon Curve and Interpolate Curve Degree and Closed Control Curve Other ways of drawing Curves Points and Curves Concept of Surface from Points and Curves Plane Planarsrf Extrude Loft Image Import (picture frame)

Surface

Volume (polysrf)

Interface

Relationship with Autocad

Concept of Volume from Surface ExtrudeSrf Create box: box / extrudeCrv / loft

Geometrical Relationship of Point, Curve, and Surface

ArrayCrv Series of ‘Duplicate’ Series of ‘Extract’ Intersect Sweep1 / Sweep2

Features Primitives Mesh MeshPolyline (from Polyline) ExtractControlPolygon (from Surface)

Create Mesh

Concept of Mesh

Rhinoceros

Basic Edit

Spatial Edit

Mesh

Useful Editing Tips

Curves Curvature

Block / Group SetPt Series of 'Select'

Curvature

Solid Blend BlendCrv Match

Concept of Solid

Creating Surface

Concept of Curvature

Use of Surface Surface Transfer

Space Test Rendering Water/ Grass/ Bump / Displacement Virtual Studio Setup

V-Ray (Rendering)

Other Features

Mesh MeshToNURBS

Basic Settings Lights Light: rectangle Light: spot Light: IES

Material Editor

Engine View GI: Sun GI: HDRI Output

2D Representation

Photoshop

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Scale / Scale 1D / Scale2D Rotate / Rotate3D Split / Trim Fillet / FilletSrf Offset / OffsetSrf

Surfaces Curvature

Boolean Concept of Boolean Union Difference Intersection Split

Move, Dargging, Copy, Mirror Group / Ungroup Show / Hide Trim Join / Explode Extend

Illustrator

Indesign

Contour UnrollSrf Smash FlowAlongSrf Tween Surface Shrink CurvatureAnalysis Zebra

Patch NetworkSrf Properties of each Surface

Chapter 10. V-Ray

To Learn in Chapter 10.

1) V-Ray basic settings • Install : Download the V-Ray from the Website, and install it.

• Open : Set V-Ray to the current renderer.

• Interface : User interface of V-Ray Asset Editor.

• Settings (.vropt) : Import and export V-Ray render settings.

• View : With the 'NamedView' command, current view can be stored and recalled.

• Lens Length: Change the lens length as needed.

• Renderer : Settings of Renderer tab.

• Camera : Settings of Camera tab.

• Output : Settings of Output tab.

• GI : Global Illumination, Sun and HDRI can be used as GI settings.

2) V-Ray Materials • Diffuse : Material's diffuse layer based on bitmap.

• Reflection : Material's reflection layer settings.

• Refraction : Material's refraction layer settings.

• Emissive : Material's emissive layer settings.

• Bump : Bump map settings.

• Displacement : Displacement map settings.

• Apply Material : How to apply materials from V-Ray Asset Editor.

• Mapping : Change the material mapping properties.

3) V-Ray Lights • Rectangle light : Place a rectangular light.

• Spot light : Place a spot light.

• IES light : Place an IES light.

4) Application in Architectural Works • Space Test Rendering : Implement V-Ray to help designer make decisions while modeling.

• Virtual Studio Setup : Scene settings to emulate a dark room for a photography studio.

• Exterior and Interior : There are different camera settings for exterior and interior renderings.

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1) V-Ray basic settings Initial settings to start rendering.

10.1.1 Install Download V-Ray for your version of Rhino from the developer’s website (https://www. chaosgroup.com/vray/rhino#). Trial version gives users 30 days to use V-Ray without any limitation of features.

The website also provides a variety of tutorials, sample files, and information for supporting users.

Open and install the installation file just as you would for installing other software.

10.1.2 Open Before opening V-Ray, one more step should be taken: 'Current Render' setting. Open Rhinoceros, click 'Render' in the menu bar, click 'Current Renderer', and select 'V-Ray for Rhino'. Now, current renderer set as V-Ray. After clicking 'V-Ray Asset Editor', user can see a window of V-Ray Settings. By clicking on the small arrow marks (red rectangles on the left figure) the window can be expanded.

10.1.3 Interface There are four main categories for render settings and the frame buffer in the top menu (the red rectangle on the left figure): Materials, Lights, Geometry, Settings, Rendering button, and Frame Buffer.

In each category, user can change the setting of the corresponding function. In the next section we will set the rendering environment by configuring the Settings menu.

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10.1.4 Settings (.vropt) In 'Settings' window, there are twelve categories to consider: 'Renderer', 'Camera', 'Render Output', 'Environment', 'Material Override', 'Swarm', 'Raytrace', 'Global Illumination', 'Caustics', 'Volumetric Environment', 'Render Elements', and 'Switches'.

All of these settings can be saved and imported as a file in the format of '.vropt' (red rectangles on the right figure).

10.1.5 View Before users can start rendering, camera views should be set. These views can be saved through the 'NamedView' command and can be loaded after saving them.

User can easily return to the saved views after completing other tasks like modeling, mapping, etc.

Users can import views from saved .3dm files.

10.1.6 Lens Length Lens length is important when setting your view. It affects not only the depth of view by changing the vanishing point of the perspective, but also the view angle.

Sometimes it could cause excessive distortion of vertical lines of the view. When trying to render a narrow space, shorter lens length can be used. Typically the lens length of 3650mm is acceptable. Lens length of 100mm can be used for less distortion of vertical lines

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10.1.7 Renderer : CPU and GPU In this setting, users can choose CPU (Central Processing Unit) rendering or GPU (Graphics Processing Unit, or Graphics Card) rendering.

Generally, without a high-end GPU, using CPU is recommended. But with a high-end or multiple GPUs, GPU rendering would be much faster than CPU.

10.1.8 Renderer : Interactive In V-Ray, there are two types of rendering.

One is static scene rendering and the other is interactive rendering. Interactive rendering shows the rough rendering to instantly respond to the changes in the Rhino scene.

If rendering is too slow, adjust the 'Ray Tracing' option in the 'Advanced Settings'.

However, since it is difficult to set up, it is recommended to refer to the manual on the official site.

10.1.9 Renderer : Quality and Denoiser The Quality slider can easily control the quality of rendered images without dealing with the complicated settings. The higher the quality, the longer the rendering time. When doing a test rendering, medium or low quality setting is sufficient, and when doing a final rendering, high or very high quality setting is recommended. Denoiser is a special feature in V-Ray to reduce the noise of the rendered image, making it clearer and sharper.

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10.1.10 Camera : Type In the Camera Tab, user can choose the camera Type. There are three types of cameras, 'Standard', 'VR Spherical Panorama', and 'VR Cubemap'. 'Standard' is the default setting. It works like a camera in the real world. In 'Advanced Settings', user can change ISO, F-Number, Shutter Speed, and White Balance just like a real camera. 'VR Spherical Panorama' can create panoramic images, and 'VR Cubemap' can create cube-map images.

10.1.11 Camera : Exposure It is recommended to adjust the settings as you would with an actual camera using advanced settings to control the brightness of the image. However, if you are not familiar with using a real camera, you can change the brightness simply with the 'Exposure Value (EV)'. The value 10 is the default, based on Rhino's default background settings. If you change the background settings, exposure value should be changed as well.

10.1.12 Output In this setting, image size and ratio can be defined. You can choose preset 'Aspect Ratio' (e.g. 16:9), or can define your own ratio by selecting 'Custom' (e.g. 13.5 : 9). In the case of portrait images, the ratio should be defined as the width being smaller than the height (e.g. 1.5:2).

Generally, more than 2000 pixel for either the width or height of the image is recommended for the final rendered image.

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10.1.13 GI : Sun and HDRI GI means 'Global Illumination', which is a system for simulating 'Indirect Light'. Indirect light is how light is bounced off of surfaces onto other surfaces. Indirect light is what makes a rendering look more realistic. Using only direct light that comes directly from the source will result in an unrealistic rendering. In V-Ray, there are two major ways to set GI: Sun and HDRI. Sun creates indirect light based on Rhino Sun settings, and HDRI creates indirect light based on a HDR image.

10.1.14 GI : Sun and Sky setting Using Rhino Sun seems quite complicated, but the result is amazing when used well.

The use and development of the Rhino Sun feature in V-Ray has continuously evolved.

To use the Sun as GI, a sun must be created first. Click the small arrow on 'VRay Lights' icon to reveal the different types of light and click the 'Sun' button, or type the '_sunlight' command. Afterwards click on any location in the modeling space. The position will not affect the lighting direction.

Sun settings can be adjusted in both V-Ray and Rhino interfaces. In Rhino, go to 'Panels' tab in the toolbar, click the 'Sun' button. The Sun Setting window will pop up. In the 'Sun Options' tab, if 'Manual control' is checked, user can manually change the sun's position according to the azimuth and altitude.

Without 'Manual Control', user can define the sun by clicking on the map or selecting the desired city, and defining the exact date and time.

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The next step is to connect the sun to the V-Ray settings. 1) Go to V-Ray Asset Editor and click Settings. Expand the 'Environment' tab by clicking the small arrow. 2) Click the 'Texture' button which is next to the 'Background' feature. 3) Click the 'Texture Type' in the first row of the texture window. 4) Select 'Sky'. 5) Choose your VR sun light. 6) Change the 'Intensity' and 'Size Multiplier' to control the brightness of the scene and shadow's rigidity. 7) Change the 'Ground Albedo' to control the color balance of your scene. 8) Usually, checking 'Invisible' button is recommended to hide sun itself. 9) Click the 'Back' button to confirm the settings and go back to the editor.

User can use the 'Rhino Document Sun' instead of the V-Ray sun. However, it is important to connect the sun to the background as the lighting texture of the scene. While it might seem complicated, this is a typical way to handle textures in V-Ray.

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10.1.15 GI : Sun - Intensity Multiplier Intensity multiplier slider provides users to control the sun light's intensity. The larger the value of the slider, the brighter the light is in the image. Thus, it is important to set the proper value.

The pictures on the left show variations of the sun intensity. From the top to bottom row of the left figures, the values of the intensity multiplier are 0.1, 1, 10, 30.

In general, 0.8-1.1 is recommended.

10.1.16 GI : Sun - Size Multiplier Size multiplier slider provides users the ability to control the sun's size. The larger the value of the slider, the more blurred the shadow edges are in the image. Thus, it is important to set the proper value.

The pictures on the left show variations of the sun size. From the top to bottom row of the left figures, the values of the intensity multiplier are 1, 10, 50, 200.

In general, 5-20 is recommended.

10.1.17 GI : Sun - Turbidity and Ozone Turbidity and Ozone sliders affect the color tone of the sun light. In turbidity, the larger the value of the slider, the hazier the atmosphere is in the image. In ozone, the larger the value of the slider, the more blueish the sky is in the image.

The pictures on the left show variations of turbidity and ozone. From the top to bottom row of the left figures, the values of (turbidity, ozone) are (2.5,0.35), (10, 0.35), (2.5, 0), (2.5, 10).

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10.1.18 GI : Sun - Albedo Color Albedo color slider and color tab provide users the ability to control the ground color.

Users can change the color of the ground using the color tab, and the intensity of the ground color.

The pictures on the left show the variations of the albedo colors. The first picture on the top left is the default albedo value, the second, top right, is black albedo, the third is orange albedo, and the last is light blue albedo.

10.1.19 GI : Sun - Blend Angle Blend angle slider provides users the ability to control the angle in degrees where blending will occur between the horizon line and sky. The larger the value of the slider, the more blended the sky is in the image.

Thus, it is important to set the proper value.

The pictures on the left show the variations of the blend angle. From the top to bottom row of the left figures, the values of the intensity multiplier are 0, 5.739, 10, 90.

10.1.20 GI : Sun - Horizon Offset Horizon offset slider provides users the ability to control the height of the horizon line. The larger the value of the slider, the lower the horizon is the image. Users can control the height of the horizon location in the rendered scene by adjusting this value.

The pictures on the left show the variations of the horizon height. From the top to bottom row of the left figures, the values of the intensity multiplier are 0, 5, 15, 50.

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10.1.21 GI : HDRI HDRI GI is an indirect lighting system that uses a special type of image called HDR (High-Dynamic-Range). The file extension of this image type is .hdr and has a wider range of light representation than typical image file such as .jpeg. On the internet, users can download HDRI images for free or with payment.

The advantages of HDRI is that users don't have to set delicate scene settings to create realistically rendered images. This is because HDRI already contains lighting (direct and indirect) and background information that can be set at once. Users only need to choose the appropriate HDRI that best suits the scene atmosphere. The pictures on the left are showing four different kinds of the sky using HDRI. Diverse cloud conditions and sky colors can be easily applied by simply changing the background image. Compared to the Sun light system, users can more easily simulate a natural sky background with HDRI. 10.1.22 GI : HDRI + Sun Sky Sometimes using HDRI is not enough to create a dramatic tone in the image. This is because sometimes it is difficult to control the shadow properties with HDRI. If users want to obtain a harder edge for shadows, they may have to adjust the HDRI in Photoshop to control the direct light source.

However, when using the Sun sky system with HDRI background, it would be easier to control the shadows in the image. The

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four pictures on the left shows the variations of the sun's size and intensity with the same HDRI background settings. In this case, users do not have to connect the sun to the background texture.

Background settings is connected to the .hdr file, and the sun is independently in the modeling space as a direct light source. After choosing the right positions of the sun based on the HDR images in the background, control the intensity and size of the sun that best works with the background.

Setting a .hdr file as a background is similar to setting an image as a texture. 1) Go to V-Ray Asset Editor and click Settings. Expand the 'Environment' tab by clicking the small arrow. 2) Click the 'Texture' button which is next to the 'Background' feature. 3) Click the 'Texture Type' in the first row of the texture window. 4) Select the 'Bitmap'. 5) After clicking the folder button, choose a .hdr file in the popped up window explorer. 6) Change the value of 'Type' under 'Texture Placement' tab as 'Environment' and 'Mapping' as 'Spherical'. 7) Adjust ground level using 'Ground' tab.

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2) V-Ray Materials Create and apply materials in Rhino 10.2.1 Diffuse: Bitmap In general, V-Ray material has three default layers: diffuse, reflection, and refraction.

Diffuse is essential and is the most basic setting to simulate real material.

In diffuse layer, users can control the material's color and texture. Without using texture mapping, users can change the material's surface color easily by choosing a solid color through the color button.

Furthermore, with texture mapping, users can change the material's surface texture easily to create realistic materials. The process to set an image-based texture is like the process of applying HDRI to the background. Click the texture button next to the diffuse color tab (a small red rectangle in the picture on the left). Then click the 'Texture Type' in the first row of the texture window. Select 'Bitmap' and after clicking the folder button, choose any kind of image format file in the popped up window explorer. From now on, this process will be referred as 'applying a texture map'. This process is frequently used and essential in V-Ray material settings.

Except for glass and metal, this process is used to create almost all texture in architectural design, such as wood floors, brick walls, concrete walls and floors, plaster wall, and even furniture. It is important that users pay attention to the quality of the texture maps. Good texture map images not only have the nice image quality but also is well cropped to create a seamless tiling.

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10.2.2 Reflection Reflection layer creates the material reflections. If users want to add some reflections to their materials, this layer should be added. Users should keep in mind that in the real world all material has some degree of reflection, however small it may be. Thus, the key to creating a realistic material is to simulate the reflection as much as possible.

In the reflection layer, there are four main parameters to control the reflection, 'Reflection Color', 'Highlight Glossiness', 'Reflection Glossiness', and 'Reflection IOR'.

Usually, to make a clear reflection like resin surface, reflection color is white. However, like gold, silver, anodized aluminum, and colored plastic, users can specify a color for the reflection by changing the 'Reflection Color'.

Also, they can control the reflection intensity by adjusting the 'Highlight Glossiness' and 'Reflection Glossiness' parameters. The larger the value of the slider, the more amount of the reflection is created in the rendering image. More specifically, if 'Reflection Glossiness' is set at a high value, more light will be reflected to other materials. In general, for materials with a high gloss finish, 'Highlight Glossiness' is set at 1.

IOR means 'index of refraction'. 'Reflection IOR' is the one of the material properties, based on the refraction rate of the material.

On the internet, users can easily search for the reflection IOR value of specific materials.

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10.2.3 Refraction Refraction layer creates the material's refraction, which helps users to create transparent materials like glass. Without refraction and only with transparent value, it is impossible to create a realistic glass or transparent liquid material. Like the reflection layer, refraction can also be created by adding refraction layer.

Click the toggle button of the refraction layer to set the refraction.

Refraction is determined by two main factors. There is a color that determines which light to refract, and transparency to show the degree of transparency according to the set color. In color, white can be understood to refract all light, and black does not refract any light. However, when creating glass material, it is important to note that refraction only functions to refract (pass and distort) light. The transparency of the actual material is adjusted by the value of the transparency slider in the diffuse layer.

Fog is an option to control the density and color of transparency. Translucency is used to express semi-transparent materials such as candles, milk, and jade.

Refraction IOR is a material property. The refractive index rate of water and glass is already set at 1.33 (at 0° C) and 1.55 (ordinary glass) in the IOR table. This table must be referenced in order to acquire the correct refractive index rate of the material.

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10.2.4 Emissive Emissive layer provides user the ability to create a light source using material. This feature can help users create self-illuminated materials (e.g. computer screen, neon sign). However, this kind of light is different from V-Ray light objects. The relationship between the V-Ray light and emissive material is respectively like the light from the lightbulb and glowing glass of the lightbulb itself.

Light from a lightbulb illuminates other objects, and the lightbulb itself has its own light emission.

Some users have a rendering method that uses materials with strong emissive layers instead of light objects. This method is not recommended as it can get messy with noise and unnecessarily prolong the rendering time. Therefore, emissive material should be used only when the material itself emits light.

Emissive properties are determined by two main factors. There is a color that determines which light to emit, and transparency to indicate the degree of transparency according to the set color.

Color determines which color to be emitted, and transparency controls the brightness of the emissive light. The intensity of the light is controlled by the number next to the color. When the value is less than 1.0, the light emission effect is insignificant. If emitting light from both sides of the object is desired, check 'Emit on Back Side'.

In architectural work, emissive material is often used to represent lighting fixtures and to express light bulbs or objects that appear to be glowing.

The use of emissive material not only maximizes the effect of the interior scene, but also greatly affects the exterior night scenes.

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10.2.5 Bump Bump mapping, or ‘Bump’ in short, is a graphic technique to shade bumps on a surface based on a texture map without physically changing the surfaces. It appears to have texture with depth, but in reality, it does not.

Because of this nature, using 'Bump' uses less computational resources and renders an image relatively faster than physically modeling the bumps.

To use bump mapping, click the toggle next to ''Bump/Normal Mapping' in the 'Maps' tab.

Then, click the 'Texture' button next to 'Bump Map'. Do the 'applying a texture map' process with a bump map file. With the 'Amount' slider, users can control the depth of the bumps.

Bump maps can be used to express unevenness of materials' surface in the distance. However, when viewed from a near distance, this unevenness may seem unnatural. If the maximum depth of the bump is too deep, the higher depths will become unperceivable. In architectural design, it is often used to express mortar joints of bricks or to express the texture of tiles' grout.

Since the materials provided by the V-Ray have their own bump maps which are already connected to the material settings, in most cases users do not have to manually link the bump map. However, if users download material files or texture map files from the internet, they will need to manually link the files. Bump mapping increases rendering time, so it is recommended to avoid using them in test renders.

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10.2.6 Displacement Displacement or displacement mapping refers to a kind of image file that is applied to the surface of an object. This image file is comprised of gray tones. Unlike bump mapping, when applied, the phase change (position difference) occurs from the original object surface. This phase change modifies the physical shape of the object.

To use displacement mapping, click the toggle next to ''Displacement' in the 'Maps' tab. Then, click the 'Texture' button next to 'Mode/Map'. Do the 'applying a texture map' process with a displacement map file. With the 'Amount' slider, users can control the depth of the displacement texture's height.

When 'Keep continuity' is checked, it can produce a connected surface, without any tear in the surface.

Displacement maps can be used to express the unevenness of materials' surface by changing their surface texture. This allows users use it in both short and long distance.

However, it requires a lot of time and computational resources, since it changes the object's surface and calculates the lighting based on the more articulated surface. Thus, to save rendering time, lowering the value of 'Amount' and using '2D Displacement' mode are recommended.

If the rendering time is too long despite changing these options, it is recommended to lower the 'Max Subdivs' value.

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10.2.7 Apply Material So far, we have learned how to create a material and how to use various layers to express materials that match the properties of the material we want to represent. There are two ways to apply this material to the Rhino model. One is by setting the material according to the layer, which affects all objects in the layer. Another is to apply material to the object itself, which affects only the selected objects.

10.2.8 Apply Material : To Layer To apply a material to a layer, right-click on the material, and click 'Apply Material to Layer'. Then the menu shows the layers in the Rhino model. Select the desired layer.

Unfortunately, users cannot set up multiple layers at once using this process.

Users can select multiple layers in the Rhino Layers panel and apply the V-Ray material in batches.

10.2.9 Apply Material : To Selection To apply a material to an object, first select the object to which the material will be applied. Right-click on the material, and click 'Apply Material to Selection'.

Applying material to an object takes precedence over applying material by layer.

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10.2.10 Mapping Once a material has been created, the way it will be applied to object(s) needs to be defined. Applying a material is like attaching a thin layer of material to the surface of an object. Therefore, users must define attributes such as whether to project it in a box form, rolled into a cylinder, pasted repeatedly, pasted only once, and so on.

After selecting an object, click the properties (properties, F3), click the 'Mappings' tab to switch to the Mappings configuration window. Several icons will appear. ‘Box Mapping’ is most commonly used in architectural design. While it is the only one mapping method covered in this chapter, other methods are very similar in their processes.

1) After selecting the object to apply the mapping, press the [F3] key or enter the command ‘Properties’ to open the Properties window. 2) After switching to the Texture Mapping tab, click on 'Apply Box Mapping'.

3) Draw a virtual box (called widget) that represents the mapping unit. Afterwards, the end cap option is available. 4) Selecting and modifying the widget like a normal Rhino object using commands such as scale1d, scale2d, rotate, and move will change the material mappings. Use widgets for faster and more intuitive mapping. 5) Enter the desired XYZ value to change the size. The larger the value, the larger the map, and the smaller the value, the smaller the map. 6) In addition, rotation can be applied.

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3) V-Ray Lights Create different types of light objects.

10.3.1 Rectangle light In a rendering, lighting is an object that illuminates other objects. There are many kinds of lights, 'Omni (Point) Light', 'Rectangle Light', 'Spot Light', 'Dome Light', 'IES Light', 'Sun Light', 'Directional Light', and so on. Using these light objects, the interior scene can be expressed with graphic realism and richness.

In addition, the appearance of the building can be represented more dynamically. In order to do this, it is necessary to know the roles and functions of the different kinds of light objects.

Rectangle Light, Spot Light, and IES Light, which are mostly used in architectural design work, are the main focus of the chapter. Based on this knowledge, other types of light objects can be learned by referring to the manual on the developer’s website.

1) In the V-Ray toolbar, click the 'Light' tab and select the 'Rectangle Light tool'. 2) Like drawing a rectangle, draw one side of the rectangle.

3) Then draw the other side of the rectangle.

4) When an arrow mark appears, user can see that a rectangle light object is created. 5) The arrow indicates the direction of the light.

If desired, users can flip it to the opposite direction by using the ‘Flip’ command.

After creating a light object, in ‘V-Ray Asset Editor’, lighting can be adjusted in detail. Click the 'Light' tab to change the color and intensity of the light. It is important to keep in mind that the intensity of the actual illumination of the rectangle light is also determined by the size of the light. The larger the rectangle is, the more intense the light is.

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10.3.2 Spotlight The ‘Spotlight’ is defined by the target area and the location of the light source that illuminates the target area.

1) In the V-Ray toolbar, click the 'Light' tab and select the 'Spotlight tool'. 2) Like drawing a cone, draw a circle to define the target area of the spotlight. 3) Then draw the starting point of the spotlight as the light source. 4) Modify the light object using edit commands such as scale, rotate, and move.

5) As with rectangular light, users can control the color and intensity of spotlight.

It is important to avoid locating the vertex of the cone that serves as the light source to conflict with a surface. If this vertex intersects with a surface, the light will be blocked by the surface.

Also, to obtain more realistic brightness, the brightness unit can be changed to Watts (W) and be considered as real world light fixtures. However, it is not always necessary to add V-Ray light objects exactly as the real world conditions. Doing so might make sense for an interior rendering, but when rendering a high-rise building, only a selective addition of light objects could be sufficient. It is sometimes advantageous to put the illumination different from the actual conditions and only in certain areas. In this case, point lighting is more advantageous than other types of lighting. Point light emits light by spreading it in all directions like a lightbulb.

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10.3.3 IES light IES light is based on an IES file (a kind of map file in which the intensity and shape of illumination are recorded). For the other types of light mentioned above, the spread of light is constant without any change to its intensity. On the other hand, IES light object can change the shape and intensity according to the IES file.

1) In the V-Ray toolbar, click the 'Light' tab and select the 'IES Light tool'. 2) Like drawing a cone, draw a circle to define the target area of the IES Light. 3) Then draw the starting point of the IES Light as the light source. 4) Modify the object using editing commands such as scale, rotate, and move. 5) As with rectangular lighting, users can control the color and intensity of the lighting.

Like spotlight, it is important to avoid locating the vertex of the cone that serves as the light source to conflict with a surface.

If this vertex intersects with a surface, the light will be blocked by the surface. Users can download the IES file that is based on the actual product from most lightbulb manufacturer’s website. Too much use of IES light objects may result in overall light scheme that is messy. Therefore it is recommended to use it only when it is needed.

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4) Application in Architectural Works Learn how to efficiently use V-Ray in architectural design.

10.4.1 Space Test Rendering So far, we’ve covered the basics on how to render using V-Ray. Render settings can be saved as a .vropt file, so that users can easily load it whenever they want. As long as users are not attempting a final rendering, they can model in Rhino and experiment iteratively with the spatial qualities through rendering.

This is faster and more economical than creating a physical model. Not only is it possible to capture the atmosphere of the space by applying material, but it is also useful to design the space during the conceptual design stage and confirm the design by seeing perspective views of the space.

To engage in this process, a fixed 'view' of the space is needed to render iteratively. Set the view to be rendered, and save the view using the command 'Namedview'. And when there is a change to the design, the change can be reflected by another rendering. By comparing the series of images, designers can create a design process similar to photographs of physical models.

The three pictures on the right show the process of developing the design of one space with renderings. Considering the given situation, the designer will develop design intent one step at a time. At this time, each change can be tested with a fast rendering to inform design decisions. Without having to waste time adjusting and reinstating settings each time, design testing using a fixed setting is recommended. This can be used to make highly efficient design decisions.

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10.4.2 Virtual Studio Setup A picture of physical architectural model can be created by computer rendering. This is a necessary process to show an overview of building or masterplan in the early stages of the design process. Many offices still make physical models, but due to lack of budget or time, computer rendering is sometimes used in its place. In this case, it is possible to generate the result quickly by using the saved rendering scene. Setting up a virtual studio environment to render pictures of the model is not the same as rendering an interior or exterior view of a building.

3. Rectangle Light2

2. Rectangle Light1 Object

Users can use the HDRI to record the studio's light environment, but using only light objects to set up the studio environment has the benefit of not requiring additional files.

First, it is necessary to add four light objects.

As shown in the figure to the left, the first

4. Omni Light

1. Rectangle Light

rectangle light should be placed in front of the model. The second and third rectangle lights are added symmetrically on both sides of the models. The fourth light is an omni light that controls the overall brightness and contrast. To simulate natural light, set the color of the light on the right side as light blue, the color of the light on the left side as daylight, and input the appropriate brightness for all lights. This allows the models in the middle to receive both bluish light and daylight.

Users can set the angle of lights to be similar to the picture on the left, and users can fine tune the atmosphere, shadow, and intensity

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of the lights by adjusting their positions and angles.

Set all lights to 'Invisible' so that users can render from various angles. If the light objects are not set as ‘Invisible’, the rendering result may include the light object itself. Set the color of ‘Background’ as black and the exposure value to be in between 9 and 11 to create a darkroom environment.

To achieve a bright and seamless background, in real life a large roll screen is installed on the floor and behind the model.

To accomplish the seamless look when rendering, it is important to use the ‘filletsrf’ command to create rounded edges. Set the material of this screen as solid white. Move the position of the lights so that the entire screen is brightened.

This setting does not result in hyper realistic rendering, but it has the advantage of achieving good quality results in a short period of time. Once the user stores their render settings and scene file, they can easily access and use them whenever they want.

V-Ray settings file and the Rhino Render scene file that were used in this chapter can be downloaded from the following website. (www.jinmorhee.net)

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10.4.3 Exterior and Interior The settings should be different when users are rendering the outside or inside of a building. This is the same principle as taking a photograph. Depending on where the photograph is being taken (i.e. outside vs. inside), the lighting conditions differ dramatically. When rendering an exterior scene, indirect illumination of HDRI is dominant but not so much for the interior light objects.

In this case, it is recommended to fix the lighting setting and adjust the rendering scene through the camera settings. This is the same as taking a photograph of a building from the outside. It isn’t that the actual light conditions are changing, but it is more about the same principle of adjusting camera exposure, F-number, shutter speed, ISO, and white balance accordingly.

Again, rendering is like taking photographs.

It is necessary to develop a tone for your rendering that fits your individuality, just as there is a photograph style that fits your personality.

For more information, refer to the official manuals and tutorials.

Help Docs : https://docs.chaosgroup.com/ display/VRAYRHINO

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