Author Topic: Bitmap import scaling  (Read 156 times)

Dr PR

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Bitmap import scaling
« on: September 02, 2017, 08:33:40 AM »
DesignCAD imports bitmap images at apparently random scaling. Actually, it seems that bitmaps are imported at a 1:1 pixel scaling with the main window. But if you import the same image twice, and change the zoom factor between imports, the same picture appears at different sizes (scales). This makes it difficult to import several scanned images that are part of a larger drawing all at the same scale.

The "File/Image/Load Image File" command dialog should have an optional provision to state the dots per inch (dpi) or dots per millimeter for the image file. Then the image should be imported at that pixel density.

For example, if the units are set to inches and the image is 300 dpi, the image should be scaled to have 300 pixels per inch in the DesignCAD drawing.

Even if a unit has not been assigned to a drawing, the image should be imported at the defined dpi using the default drawing units (even if you haven't assigned a drawing unit the program does have an internal default drawing unit so everything draws at the same scale).

This would insure that images created at the same dpi all import at the same scale. It would also allow the user to control the scale of bitmap imports for multiple drawings by defining the dpi each should be imported at. For example, if a map created at 24,000 feet per inch was scanned and then another map at 48,000 feet per inch was scanned, the first could be imported at 300 dpi and the second at 150 dpi and both would appear at the same scale in the DesignCAD file.

Phil
DesignCAD user since 1987