Settings of Raster Snap

Min Length:

This parameter defines the minimum size of a raster object that can be recognized.

To set Min Length:

•    Click  button and specify distance (2 points on raster line) that should be recognized as line.

or

•    Enter value to the field.

Max Width:

This parameter defines the maximum width of raster lines that can be approximated by lines, arcs, circles, and polylines.

If the width of a raster line exceeds Max Width value, then the only possible recognition mode is Auto tracing and approximating with an outline object.

To set Max Width:

•    Click  button and specify by 2 points maximum width of raster.

or

•    Enter value to the field.

It’s better to set this value a little more than maximum width of the thickest line in the image.

Max Break:

Sets the length of the maximum ignored breaking raster lines.

If a raster line is broken into parts it should be traced as an entire object, then the value of Max Break should be set to the largest gap between the raster line parts. The program will ignore the breaks and create single vector object, approximating the whole raster line. By setting a comparatively large value of the parameter, users can, for example, trace dash-dotted raster lines, and arcs as single entities.

To set Max Break:

•    Click  button and specify by 2 points the largest gap between the raster line parts.

or

•    Enter value to the field.

Accuracy

This parameter determines the accuracy of approximation of the original raster object with a vector one. If the original image is distorted (for example, circles have the form of ellipses), then reduce the value of the Approximation Accuracy parameter. However, this leads to inaccuracies in recognition, for example the program might take a short arc for a line. When the quality of a raster image is high, increase the value of the Approximation Accuracy parameter.

Sometimes before tracing the quality of the raster image can be improved by application of a smoothing filter.

To set Approximation Accuracy:

•    Move slider.

If the original raster entities are distorted (for example, raster circles have an elliptical shape), recognition accuracy will increase when moving the slider to the left, to the Min value. If the original raster image is of good quality, the slider should be moved to the right, to the Max value.