2

I'm a first time QGis user and got some resolution troubles. I need to create a DEM for whole Europe using SRTM 1-arc second (30m) from USGS. As I need the slope algorithm in a later step, I have to use a cartesian coordinate system. I'd like to use one single system, so I guess I go with ETRS89 (instead of UTM zones). When I reproject to the new CRS, the pixel sizes change from 30x30m to 26x26m (according to the measuring tool).

Can somebody explain me why this happens and if it matters?

underdark
  • 84,148
  • 21
  • 231
  • 413
dadadingo
  • 229
  • 1
  • 3
  • 11

1 Answers1

2

The 30m is a rough estimation. The actual number of meters depends on the latitude. See https://gis.stackexchange.com/a/208739 for some numbers.

PS: For Europe the EPSG:3035 "ETRS-LAEA" is recommended and widely used.

bugmenot123
  • 11,011
  • 3
  • 34
  • 69