5

I am looking for a good workflow on how to represent relief on a map as vector (e.g. for further processing in Adobe Illustrator or Inkscape). My inspiration is the present google maps at zoom level 12, since this looks like it is based on vector graphics:

Map data ©2013 Google

https://maps.google.de/?ll=47.27853,10.686607&spn=0.179816,0.41851&t=m&z=12

Starting with some free SRTM elevation data, what would be the best way to achieve such a result?

Improve this question
4
  • I'll be interested to know, why you think this is based on vector graphics. mts1.google.com/vt/… is very much an image.
    – Devdatta Tengshe
    Oct 4, 2013 at 5:46
  • 2
    Google Maps is a rendered image of course. We can not be sure whether they used a vector base layer before rendering this. However when looking closer at the terrain shading I see relatively large patches of homogeneous color. They seem to use four colors only in the grey spectrum to represent the terrain shading. I thing that might well be possible as vector data without producing too large datasets. When you swith on "Terrain" in Google Maps you get a different view with a relief shading that uses gradients. That in contrast looks really like it is based on raster layer.
    – Chris P
    Oct 4, 2013 at 7:27
  • What software do you have?
    – Devdatta Tengshe
    Oct 4, 2013 at 8:44
  • I use QGIS + Adobe Illustrator and Photoshop
    – Chris P
    Oct 4, 2013 at 9:43

1 Answer 1

Reset to default
6

This is how I managed to get it done in Qgis:

  1. Generate the Hillshade using Raster>>Terrain>>Hillshade Analysis.

  2. The Hillshade that was generated in my case, had values from 25 to 190, with values clustered around 150. Using the Histogram, I figured out what would be the values of the 4 classes.

  3. The Hillshade now needs to be reclassified. In Qgis 1.8, there was a plugin called RasterCalc, which has not been updated to QGIS 2.0 API. SO I fired up Qgis 1.8 and reclassified the Hillshade Raster into a new raster with 4 classes.

  4. I used Raster>>Conversion>>Polygonise to convert the raster from step 3 to a polygon shapefile.

Once you have a shapefile, There are several ways of exporting to Illustrator, most of which are lossy.

I created a map in map composer and then exported that to pdf, which I belive can be opened by Illustrator. You can also export to SVG, which could also be used.

Please note, that I wasn't too happy with my polygon output, so I'm not sure how useful this procedure would be.

Improve this answer
1
  • Since this workflow still helped me 9 years later: Since QGIS 3.20 there is a native algorithm to reclassify rasters: "Reclassify by table"
    – sidapo_cartisan
    Jun 23, 2022 at 6:34

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.