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Whats the use of CTB
I’m a land surveyor and i whenever i send drawings to civil engineers they ask me for CTB files. I dont use ctb, since my drawings are black and white and i plot them on printing facilities. Whats the meaning of ctb files and why would someone use them
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30 Replies
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I believe it contains all the pen weights etc. If you don’t have the associated .ctb file the plot will not look like it should.
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This is what i dont understand. Since i dont own a specific plottter, or have any color information to do the mixmatching, and each line has each corresponding information, why use pens in the first place?
Lets say i have weighted polylines, and inside the properties dialog they have their corresponing width. What more will a pen weight do, to help a fellow engineer
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Interesting. First, let me clarify that CTB files are not specifically for plotter information. That is handled in PC3 files. CTB files were the original way to deal with pen weights in AutoCAD. Now, I’ve never done a drawing in the manner you describe, nor have I ever received a drawing in that manner, so this will just be an educated guess.
You’re right. The way I envision it, they shouldn’t need a CTB file from you. A polyline with a width will plot the same regardless of its pen weight. If you use true type fonts, they also will plot the same regardless of its pen weight. If you don’t use true type fonts, then they won’t.
So why are they asking for one? Did they actually try to print it and have it not come out the way they would like? Be aware that if they try to use None as the Plot Style Table they will get color plots regardless of your intent, unless you make all your layers color white. You could suggest that they use the standard Monochrome CTB file. I think that would work for them.
They also could just be asking because they are used to plotting with them and can’t wrap their heads around not using one. I prefer using STB files rather than CTB files, but even with that, I don’t ever ask a surveyor for their CTB file because in the end, I want to be able to use my STB file to plot drawings, so I always edit a surveyor’s drawing file to match my STB file for desired pen weights (light), and screening.
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I use a ctb file because it allows me to use many different colours in the Cad drawing to aid in drafting and then plot in black and white using the ctb. Also it allows me to use screening which makes the printed drawings look really well.
I used to do something similar to you previous to using the ctb but would not do it any other way now.
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I use the pen weights assigned to the layers then as Totalsurv says I have a CTB file which plots the first 7 colors black. So I can use any of the first 7 colors I want for on-screen viewing purposes and it will still plot black per the lineweight assigned to the layer.
The ability to set lineweights came in, what, 20 years ago? Yet most are still plotting a given lineweight by color which I find aggravating. What color is a 0.7mm lineweight again? The one that looks like light pink chartruese. what?
CTB files came from back in the day of pen plotters when say red would plot to pen 1 and yellow to pen 2, etc.
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As Dave mentioned, CAD started using WYSIWYG about 20+ years, in place of pen tables ( and pen plotters).
WYSIWYG = What You See Is What You Get
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CTB is a color table used by AutoCAD. The different colors represent the line thickness. If using C3d 2015 or newer, you can plot by STB (style table) which color doesn’t matter, if you want thicker lines then the user changes the lineweight.
T. Nelson – SAM, LLC -
I use an stb (style based) so that line weight is primarily controlled by layer. If I want a layer or object to be in color I set the style to “normal”, “style1” gets me solid black lines with the weight by layer, and “style2” is set to give me 50% screening with the line weight still controlled by the layers.
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@squirl Not throwing rocks, but I started with AutoCAD 13 on Windows 95 and it had STB…….most folks just didn’t use it. Oddly, I think vanilla AutoCAD still defaults to CTB out of the box if you use their drawing templates.
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After about 30 years a work flow becomes very natural. If you started with CTB you probably still use it. Not a hard and fast rule but very common. We are creatures of habit and rarely change course without good cause. Even then it may not happen..
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Just a thought. That office hasnt upgrafed to latest versions of Autocad and stills uses 2007. Maybe thats why they ask for ctb files?
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First, let me say that BlitzkreigBob and Dave Karoly have already said most of what I have to say about this matter.
“ctb” stands for “color table”. It has its roots in the days when plotters had actual pens in them. And the layers had much more limited options. In the earliest iterations of ACAD you had color, on/off, freeze/thaw settings and not much else. If you were lucky enough to be working with a color plotter. There needed to be a way to associate the color of an entity to a certain pen in the carousel. So ctb files were created.
The ctb file can also be used to control plotted linetypes. You could be looking at one linetype on your screen and get quite another when plotted. For some reason this never stuck, but the lineweighting has. As thebionicman says, its a habit. People do it because they always have without knowing why. Ugh.
I use a slightly modified version of monochrome.ctb, which comes “out of the box” with standard installations of ACAD. I’ve modified a half dozen colors to plot in color. This only for the last couple of years. Monochrome just prints everything in black at the entity lineweight and linetype. If you use no ctb file at all you are going to get prints in the same colors as on your screen.
@Stephen Ward – I’m sorry but stb’s were a failed experiment, IMHO. You can now achieve everything you did with stb’s by setting up your layers with lineweights and linetypes. If you try, with stb based files, to collaborate with the outside ctb using world you are going to cause problems. Perhaps its different now but back in the day when I was briefly forced to go the stb route the conversion was a one way street. You could convert ctb based files to stb, but you couldn’t go back.
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I’m sorry but stb’s were a failed experiment, IMHO
I’ve been using STBs since they were first introduced. The “experiment” has been very successful here.
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@norman-oklahoma Ford vs. Chevy ???? ……….I suspect it has more to do with when you learned CAD than anything. I started in the mid-nineties when both my school and my first employer had ink-jet plotters. I’ve also always drawn in versions of AutoCAD where line weight is displayed on screen so WYSIWYG. For me color is best used for contrast on screen and to easily know what an object is by its color.
If you’re ever forced to visit the darkside again, I believe you might find the CONVERTPSTYLES command will take some of the pain out of the experience.
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Not saying that stb’s they don’t do what they do. Just saying that there are other, better ways available now. But now that the 2 of you have a stock of legacy drawings you won’t want to change. Most people use ctb’s, and it’s a CAD management problem to mix stb and ctb based drawings.
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CTB is a concrete treated base used in road construction to obtain a hardened base course. :>)
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CTB is a concrete treated base used in road construction to obtain a hardened base course.
LOL, that’s exactly what I remember CTB as. WSDOT hasn’t used it in many years now, but our pay item ticket books still had CTB listed until not all that long ago 🙂
The only superior evidence is that which you haven’t yet found. -
Once you find the right CTB you can rub it on your arthritic drawings and the swelling and pain subside.
???Ÿ
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I always send a pdf copy these days. It saves them having to look for a ctb file and allows me to show how it should be printed.
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I do pdfs as well when i want someone else to print my drawing. This saves me the hassle of having the include images fonts xrefa and whatevsr else. But sometimes they just dont go for it
So anyway i am still not sure what ctbs are. So in the old days if you wanted a line to have specific width or color ir linetype you needed to include it on a separete layer and give information on hiw that layer is printed? My god what a hassle if i understand it correctly.
So if you just wanted a red line you had to create a layer draw that line there and unstruct via ctb that they layer should print as red?
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