Invent Civil

Civil Engineering news, technology, and opinions

01 Oct, 2008

Using WinTopo to Vectorize Drawings

Posted by: Skylar In: technology

How many times have you been sent a drawing in print only to find out that an AutoCAD version is not available?  If your experience has been anything like mine, it happens all the time.  Sometimes the drawing was created before the AutoCAD era, and sometimes it was just sent by another consulting firm which didn’t want to send an original cad file.  Most times I would have to manually trace the lines from a raster image in AutoCAD.  What I didn’t know was that a program like WinTopo exists to automate the process.  Let me show you how it works in 3 (very simple) steps…

1. Download and install WinTopo from

2.  Open up the image of your choice in WinTopo and go to “Vector -> One Touch Vectorization” (or press the F10 keyboard shortcut)

Note that you may be able to obtain better results from the program by changing the default vectorization options, though the default works well most of the time.

3.  Now save the file by going to “File -> Save Vector as”. Save it as a DXF file so we can open it straight up in AutoCAD (you can save it as a dwg file later).  Once it’s saved, just open it up in AutoCAD and voila!

I tested this program out using a site plan I obtained from a simple google search:

Simple Site Plan

Now once it’s vectorized, look at how AutoCAD sees it:

Look similar?  That’s because it is.  All the linework shown in the AutoCAD drawing above is composed of polylines.  While this is great for the important features of the drawing, it also means that all the text is made of polylines as well.  Some of the linework may be choppy, and the lines are not continuous (ie they break where they cross other linework), and they will not be on any separate layers.

It may not be perfectly accurate, but it sure beats tracing out a raster image!

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