1

I am trying to calculate volume using the GRASSplugin. I have my area information in vector format and my depth information in raster. I read that it is important to set the raster resolution before using GRASS. How do I know what resolution to use? My extent is currently the entire world for this project but it doesn't need to be.

Here is a tiff of the area I am working with: It is currently in WGS84 but I will save it as a custom CRS using lambert, centered at 70degrees:

enter image description here

1

Depending on your needs, the resolution usually should be such that a few thousand cells in both the X direction and the Y direction are sufficient. If you have map layers of the whole world then a resolution of 5 kilometers would give you about 8000 X 8000 cells in your raster. That's "comfortable". But, again, you have to clearly define your needs, and choose extent+resolution to meet your aims.

2
  • I have included a screenshot of the area I am working with. This Bathymetric data will be combined with habitat areas (shapefiles) in order to calculate volume. I will be using a custom CRS as I described above. Do you have any tips of what kind of resolution I need for what I want to accomplish? Also if I ever work with a larger area will I then need to reduce resolution that what I would use here? What are the effects of using the 'wrong' resolution? – anina Sep 23 '14 at 12:41
  • I don't think anyone outside your project can tell you what resolution to choose. It highly depends on your goals. If the custom projection uses meters, then start by checking the east-west and north-south extents. And, as I said, choose a resolution which leaves a few thousand cells in each direction. And if you switch to a larger area, you might certainly decide to change to a larger resolution. – Micha Sep 24 '14 at 21:00

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.