I am trying to use the drawing filter (filters->image paint and draw -> drawing) and eventually process a photograph to a vector drawing. The problem is the results of the filter change every time I zoom in or out, and exporting the image or using make a bitmap copy doesn't give results that match the displayed filtered image. I don't think that this is the intended behavior, but I also can't find any documentation on the drawing filter.

Thanks to anyone who can help :)

The mentioned filter uses the convolve filter primitive.

That makes it render an 1 px wide "stroke" on screen when there is a sudden change in luminance, regardless the zoom level. 

It results in the mentioned behavior: the filter's effect is scale/zooming independent. 

If you are using a 100% zoom level, a bitmap copy/exported image should appear the same if put in the drawing, if they are generated at 96 dpi. 

Can set up that resolution in the export dialog or in the preferences.

Bit unsure of your process, how this method would be more beneficial than using the built in trace  bitmap function alone. 

Admittedly you can create some halftone effects with filtering, but the built in drawing filter is not giving that result.

It's similar to a regular trace bitmap where after the trace you set a white fill and a black stroke to the result.

The goal is to eventually draw the photos with a plotter at an in person maker event with a mostly automated workflow. The drawing filter seems to give nice simplified results that draw well, but perhaps I need to play with the trace bitmap settings and see what I can do.

Thanks so much for your help :-)