AutoCAD

CTB vs STB: Why STB is the Future

The topic of CTB vs STB has been a heated discussion since STB was added to AutoCAD in the year 2000. I am sure some of you CTB users reading this are already steaming and can’t wait to tell me that I’m wrong and that STB has no place in the drafting arena. I do implore you to have an open mind and continue reading, because in my experience most CTB users have been misled about what STB can actually do and how it is supposed to work.

A DIVE INTO CTB

First, we need to take a look at CTB and give credit where it is due. CTB is a very easy drafting method, you pick a color from one to 255 and the drafting is done. It’s also simple to tell someone to turn an object to “red” or “color 252”, and the change appears on the screen. The ease and simplicity of this method is where CTB has its advantage, and why many users prefer to use it. However, despite the popularity and long tenure of the CTB method, I have found a few issues with this way of drafting (see Figure 1).

The first issue is that if your company is anything like mine, you might work for multiple different clients, jurisdictions, and agencies - all of whom have a different CTB they want to use and they will not always be similar to one another (see Figure 2).

Figure 1 Figure 3

Figure 2

The second issue is related not only to drafting, but also design. Since today most designing is done right in the CAD file, being able to visually see issues and conflicts as we are working is very important. This is an area where CTB falls short. I am sure most of us at some point have drafted a CTB file where every layer not important to the sheet was relegated to one color - most likely one of the 250’s. Obviously, this causes items to be difficult to distinguish from one another. When modeled objects are all the same color, mistakes happen and issues within a project can be hard to catch until it is too late.

STB TO THE RESCUE

Now, I bet you’re wondering how STB is going to help fix all of this. First, let me start by removing some of the misconceptions and misinformation regarding what STB is and how it is supposed to be used. Most users’ experience with STB is solely running the CONVERTCTB command on their CTB file and getting an ugly STB with a plethora of different plot styles (see Figure 3).

Figure 4

Here, each plot style acts a color would in CTB. This is how most people have been introduced to STB and as first impressions go, this is not a good one. Hopefully you will give it a second chance, though, because the STB shown below is an example of how it is supposed to work (see Figure 4).

This method of STB uses the plot style to control just the screening of the layer or object. But, how do you control the thickness of the line work? The answer is in your layer manager, there is a column that controls the lineweight for each layer. This is how your STB will know how thick to plot your layer (see Figure 5).

Now we can start getting into the real benefits of STB. One thing I haven’t mentioned yet when using STB is the layer color. When using STB, the color of an object doesn’t matter with regard to how it plots. How does this help us? Well, going back to what I said about multiple objects being the same color in CTB causing problems in design, STB fixes this issue. Now that color is independent from the way an object plots, we can standardize what colors represent in our drawings. For example, green can represent sanitary sewer/wastewater-related items, blue can represent water-related items, etc. This opens up not only the ability to standardize object colors, but also allows us the ability to visually see these items on the screen and have the ability to check for design issues without all the guesswork. This would be true for any drawing that you reference your file into, and the layer color would not change throughout the entire project. This helps keeps consistency in our drawings and makes visibility within CAD files easier.

DRAFTING WITH STB

Now, I realize this adds two additional properties to control plotting, but these items won’t need to be modified in every drawing. With STB - and to a lesser extent, CTB – you will set up your base files the way you want them to appear graphically in the vast majority of your sheets. Take, for example, a water line that will need to be emphasized only on the “water” sheets. You would pick the proper screening and lineweight in your base file, then you would only have to adjust the plot style in your sheet file to set your water items to plot black. Another benefit to using STB is the ability to plot in color. Anyone who has needed to create an exhibit in color knows how beneficial it can be in the engineering world. I am constantly sending out colorful exhibits to clarify issues or to highlight problem areas. To produce a color plot in CTB, you have to use a “true color”. However, because “true colors” can’t be loaded into a CTB, you have to manually set the lineweight of an object for it to have a thickness when plotting. With STB, this functionality is already built in. If you notice in the STB, at the bottom it had two options for color: “Color 100%” and “Color 50% Screen”. By simply

switching the plot style of a layer, we can now plot in color and with a selected lineweight. The difference between these is “Color 50% Screen” applies a screening to the color and removes some of the saturation and gives a more pastel look (see Figure 6).

THE LEARNING CURVE

The question that gets asked the most when thinking about switching to STB is how long it takes to get accustomed to using STB. Unfortunately, I can’t provide an answer to this as everyone learns at a different pace. However, I can provide some insights into the areas with which people seem to have the most difficulty. The obvious one is switching from knowing a color to knowing a lineweight. When I first switched to STB I wrote down the colors I used the most and what lineweight and screening it had. As with anything the more you do it the better and faster you will get.

INDUSTRY STANDARDIZATION

One last item I wanted to touch on goes back to my earlier statement about working with CTB’s and the lack of standardization in the industry. This can be problematic for CAD managers trying to set up standards that follow multiple different CTB’s and ensuring the correct properties are being used. This issue can be significantly reduced using STB and lineweights as I have shown here. If the standard is for everyone to use lineweights, there are fewer graphical translation issues when transferring CAD files. In a similar vein, if you name your plot styles very clearly (like shown in the example STB), anyone should be able to figure out how something is going to be plotted. This makes sharing files much easier and reduces the need for every company or jurisdiction to have their own standard.

FINAL THOUGHTS

As you can see, there are a lot of benefits to using STB. Personally, as a user who has worked with both methods for a long time I have always found STB to be a more drafter-friendly approach and I hope now you do as well.

Brandon Cole is a Sr. Designer for Huitt-Zollars, Inc. He has over 16 years of experience in civil design and CAD management. His background has mainly been in urban development, but has also been a part of many federal and transportation projects as well.