I want to vectorize an old map.

Notably, this one: https://jcb.lunaimaging.com/luna/servlet/detail/JCBMAPS~1~1~2740~101255:This-plan-of-the-City-of-Philadelph#

So I am using image trace.

I tested various settings of image trace on a small, cropped version of the image. And the results were promising.

When I applied the same settings to the entire image, the results were really poor.

small,med,large image input [-rough width for each input: 1000px 2000px 10,000px]

This suggests to me that the applied algorithm is affected by the size of the initial image. So the same pixels will result in different vectors if the rest of the image is larger.

settings [above settings, applied the same to each image input

My options may be...to chop of the image into a bunch of smaller sections, vectorize, and recombine.

So, the questions: 1. Is my assumption correct, or perhaps I am missing something? 2. Is there a setting to override this change? 3. Does anyone have a better solution?

Many thanks!!

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  • 1
    I would not attempt to trace this. I'm place it on a layer, lock the layer, create a new layer above it and start manually tracing things, using the locked layer as a guide. – Scott Jul 17 '19 at 14:33

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