4

I've been trying to create a contour map of a DEM and I've been running into some technical problems. I want to avoid artifacts, so I'm using a DEM of the entire area. This means the size is rather large, over 40 gb. I then run gdal_contour to get a shapefile.

I think gdal started throwing out errors when the .shp file reached over 4gb. This is over the filesize limit of 2gb, so I did not get a finished map or valid shapefile. So I was wondering if anyone had experience working with large raster sets, and had suggestions for an appropriate file format.

Other considerations:

Space is a small consideration. I created a few contour maps of a small sample section, and noticed that the other formats were over two and a half times the size of the shapefile.

Ram is an issue. I'd like to keep ram usage minimized. I only have 16gb of ram, and I saw gdal_contour go up to 12gb of ram used. My fear is that going to a more space intensive format will increase ram usage. I can go up to 32gb of ram, but I'm also wanting to create another contour map with a higher definition, which will increase ram usage.

2

If portability is not an issue, set up a postgis database. That can take the whole world (in the form of openstreetmap data).

If you want the data to be portable, think of a spatialite database. I have not yet used such large amount of data with it, so I will be pleased to hear your experience.

To speed up processing, spatial indices can help on both databases.

  • We decided to decrease the size of the maps instead. This allowed us to use shapefiles. We should be able to deal with any artifacts along the borders by creating new DEMs centered around the AOI. – midfield99 Jan 13 '14 at 16:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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