When you scan a drawing and convert it to vectors it will not appear in your CAD program at the correct scale. This is because your scanner scans the drawing in units of measure called pixels, whereas your CAD program uses millimeters or inches etc.

To scale a vector image to the right size, use the Vector Scale Settings dialog. This appears when:

You select File Menu > Vector > Scale Options.

You have saved a DXF or HPGL file using File Menu > Vector > Save As and have clicked Yes to the Scale Prompt that appears after the save dialog.

There are three scaling options in the Vector Scale Settings dialog:

DPI

Distance

Geo

In addition, you can:

Assign coordinates to a known point

Enlarge or reduce the size of a drawing

Scale using DPI

(If your raster image contains dpi information a value will be inserted here automatically.)

For example:

If the drawing was at 1:1 enter the scale like this:

If the drawing was at 1:50 enter the scale like this:

If the drawing was at 1″ = 1′ enter the scale like this:

If the drawing was at 1/8″ = 1′ enter the scale like this:

If you are going to save the vectors as DXF select the units your CAD program uses in the Export Units part of the dialog.

If you are going to save the vectors as HPGL, select HPGL plot units as the export units.

Because HPGL files use an integer coordinate system, scaling an HPGL file may give rise to inaccuracies in the positions of vector end points.

Scale using Distance

Suppose there is a line on your image that you know represents 8 miles – for example a scale bar on a map or a dimensioned line on a drawing. The Distance scaling option lets you use this information to scale the drawing.

The Vector Scale Settings dialog disappears.

The dialog reappears and the image length of the distance you have specified is automatically entered into the Image Pixels Distance box.

For example if the known distance is 8 miles, type 8.

For example if the known distance is 8 miles, select miles.

If you are going to save the vectors as DXF select the units your CAD program uses in the Export Units part of the dialog.

If you are going to save the vectors as HPGL, select HPGL plot units as the export units.

Because HPGL files use an integer coordinate system, scaling an HPGL file may give rise to inaccuracies in the positions of vector end points.

Scale using Geo

If your raster image is a GeoTIFF file, the Geo option will be selected automatically and values from the GeoTIFF file will be automatically entered into the Geo and Tie Point parts of the Vector Scale Settings dialog.

If your raster image is not a GeoTIFF file you can use the Geo option to scale the drawing as follows:

Enter these figures into the Geo Pixel Scale X and Y boxes (the X and Y scaling factors will usually be the same).

For example, if 1 inch on a map you have scanned represents 100 inches on the ground in the X (horizontal) direction, and you scanned the map at a resolution of 300 dpi (dots per inch), then the distance represented by each pixel in the horizontal direction will be 100 / 300 = 0.3333333.

Assign coordinates to a known point

Suppose you are vectorizing a map and a known point on the raster image is at coordinate 10235,78653 on the map. In Scan2CAD you can assign the coordinate 10235,78653 to the point so that when you import the vector file Scan2CAD produces into your CAD program it will be placed in your CAD program at the correct coordinate location.

The dialog disappears.

The dialog reappears and the raster coordinate of the point you clicked on is automatically entered into the Raster Coordinate X and Y boxes.

Enlarge or reduce the size of the drawing

For example, entering 2 into the Scale X box and 2 into the Scale Y box will enlarge the drawing by a factor of 2 in both the X and Y directions.