Bitmap to DXF conversion: I agree with the other posters here that manually tracing "over" a bitmapped image is probably the quickest, best way to accomplish this. However...
There is an inexpensive CAD program available that has a unique "Auto Trace Bitmap Command" that can covert a bitmap file to a CAD format (DXF, etc.) that can be brought into SolidWorks. The product is DesignCAD, and this feature is available in the lowest cost ($89.95 list) version of the DesignCAD product line, DesignCAD Express Version 12 (
A 30 day trial version of DesignCAD 3D MAX (
which also has the “Autotrace” feature), can be downloaded at
.
This isn’t anything you’re going to want to trade-in your SolidWorks for, but this is a neat feature (and it might just pay for the $90 price tag for the Express Version, depending on how much of this type of thing you have to do). I ran into DesignCAD when I discovered that it was the only product that would directly read a proprietary, obsolete CAD file format that the company I then worked for had some 5000+ drawings in…
I don’t know how much (or if) the bitmap autotrace feature has evolved/improved since the DesignCAD Pro 2000 version I have, but I’ve cut and pasted from the help screen of that version to give you some idea of the capabilities of this feature:
“The Auto Trace Bitmap command creates vector outlines of specified colors in bitmaps. This allows the image to be manipulated in DesignCAD. With a color or black and white scanner, a drawing or other art can be scanned and saved as a bitmap, then each color can be traced to produce a DesignCAD drawing.
Bring a bitmap into DesignCAD with the LOAD IMAGE FILE command. When the bitmap is displayed, select it and choose the AUTO TRACE BITMAP command from the TOOLS menu. The Auto Trace Bitmap dialog box appears.
Select the DETECT STRAIGHT LINES AUTOMATICALLY option or the DETECT CURVES AUTOMATICALLY option or both by clicking on the check box(es). The Straight Line option detects straight lines and smoothes the resulting vectors by removing intermediate points. The Curves option deletes curves in the bitmap and smoothes the result by drawing fewer points to represent them. Also, notice the Tolerance slider bars for the Straight Line Detection and Curve Detection. To change the tolerance for Straight Line or Curve Detection, click and hold the indicator using the mouse, then move the indicator closer to LOW or HIGH.
For both the Detect Straight Lines Automatically option and the Detect Curves Automatically option a low tolerance results in short line segments. Conversely, a high tolerance for these options results in longer line segments. In the Color Detection area of the Auto Trace Bitmap dialog box, the color to be traced is displayed on the Color of Region to Be Traced: button. To change color, click this button. The cursor turns into an eyedropper.
Either in the thumbnail image at upper-right of the dialog box or in the main drawing area, position the eyedropper on the item you want to trace. Click the mouse button. The sample is taken from the color at the eyedropper tip. The Color of Region to Be Traced: button will change to the color of the item you selected.
To change the tolerance for the color to be traced, click and hold the indicator using the mouse, then move the indicator closer to LOW or HIGH to change the tolerance. Changing the tolerance for the color to be traced changes the size of the sample or "footprint" that will be taken when you select the color to be traced. All of the colors that fall within the footprint are considered a single color.
The Low setting on the Tolerance slider bar for Color Detection will take a 1 pixel sample. The next mark to the right takes a 2-pixel sample, the next a 4, the next a 6, and finally the High setting takes an 8-pixel sample. If there are multiple bitmaps in the drawing, you can click the SELECT BITMAP TO TRACE button, then click on the bitmap you wish to trace.
Once you have selected the bitmap to be traced and set all of the tolerances to the desired levels, click the TRACE button. DesignCAD will trace the bitmap. If you like the results, click the CLOSE button to close the Auto Trace Bitmap dialog box. If you do not like the result, use the mouse to click anywhere in the drawing and press Ctrl+Z for the Undo command. Change the tolerances and click the TRACE button again. Once you are satisfied with the result, select the bitmap and delete it. The new vector image of the bitmap remains in the drawing.
Note: Auto Trace Bitmap can only trace and convert one color at a time. If the bitmap image has entities in more than one color, you must execute the Auto Trace Bitmap command for each colored item you want traced.”
You can well imagine that “tweaking” of the settings (and the quality and complexity of the bitmaps) has a significant effect on the end result, and the amount of “cleanup” (and redrawing) you’ll (inevitably) end up doing. You may find (as is often the case with this kind of thing) that it would have been quicker and better to “start from scratch” manually tracing the image as has been already been suggested (the voice of experience).
But, if you read this far, you must be interested. If someone has time and inclination to download the trial version and play with this feature, it would be great if you could report back your experience/impressions here…
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