QGIS UK Scotland 6 McDonald

Ross McDonald's presentation on different ways of rendering an elevation model as a hill shaded or texture shaded image. Presented at 6th Scottish QGIS UK user group meeting.

Transcript

1. them thar hills shadin’, texturin’, blendin’ Ross McDonald @mixedbredie
2. Take one DEM Intermap 10m DTM
3. Add a colour gradient
4. Make a hill shade Note the hatching effect caused by live hill shade renderer
5. Multiply blend
6. What is texture shading? An alternative shaded relief technique Based on fractional Laplacian algorithms Emphasises drainage network Highlights the visual hierarchy Developed by Leland Brown Open source under BSD 2-clause www.textureshading.com Mac and Win binaries, compile on Linux
7. Take one DEM
8. Workflow Convert GeoTIFF to GridFloat gdal_translate –of EHdr –ot Float32 in.tif out.flt Generate a texture ./texture 2/3 out.flt texture.flt Export a GeoTIFF ./texture_image +2.0 texture.flt texture.tif
9. Texture shaded DEM
10. Coloured in
11. Blended with hill shade
12. Without texture shade
13. Blender 3D OS Terrain50 DTM See https://wanderingcartographer.wordpress.com/ for workflows
14. Uses the BlenderGIS addon - https://github.com/domlysz/BlenderGIS
15. Comparison QGIS/GDAL Quick Easy QGIS Raster menu QGIS Live renderer (press F7 in 2.16) Render artefacts  Texture Shading Download required Easy to use Some prep needed (Float32 DEM) Memory dependent Nice effect Use alone or blend Blender Separate app Steep learning curve More prep needed (Int16 DEM) RAM/CPU/GPU dependent Slow but lovely Realistic lighting
16. Inspiration http://www.shadedrelief.com/ http://www.reliefshading.com/ https://wanderingcartographer.wordpress.com/ http://mapzilla-art.co.uk/ https://owenpowell.wordpress.com/ http://www.mapsmith.net/ https://somethingaboutmaps.wordpress.com/ https://cartoblography.wordpress.com/ http://christopherwesson.azurewebsites.net/