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ajaysbharadwaj Nice issue do discuss! A) SOURCE DATA yes, Google Earth uses mostly SRTM, but in someplaces uses other sources. We don't know where or the source quality, so.. we end with a DEM with unknow quality. "NASA has released a void-filled version of the Shuttle Radar Topography Mission digital elevation model, known as "SRTM Plus" or SRTM NASA Version 3. SRTM Plus uses SRTM Version 2 (see below) where the radar interferometric method was successful (not void). Most voids are filled with elevation data from the ASTER GDEM2 (Global Digital Elevation Model Version 2)." (see http://www2.jpl.nasa.gov/srtm/) Bayond that, you can search in your Area of interest for better accuracy/Resolution DEMS Interpolation ============ I strongly disagree with you. You took grid data. get XY points (manually), and then interpolate again to a grid!!! Why don't you just use Shuttle Radar Topography Mission (SRTM) Data in Surfer?? (here go how: http://www.goldensoftware.com/Newsletter/issue52s# ) Contours "look better" because: 1) you use less source data to interpolate (if you are use the more data points you are using interpolated points to interpolate, and if you use the same data ponits you work a lot more for the same results) and most important: 2) You interpolate with a smooth/stocatic method (Kriging), and using default parameters! You can use a lot of interpolation methods (In surfer, ArcGIS, or mostly any software) Linear, IDW, Krigin, NN, Spline, Trend, etc., with o without breaklines/barrers I ussually avoid use Kriging for terrian, beacuse tend to smoth terrian breaks. Why? ¡¡¡Nice and Smooth countous dosn't mean better acuracy!!! Ussually the oposite! Regards Art

For certain areas, elevation data doesn't come from SRTM. There are few other sources as well. Also the interpolation method used in GE looks better than the ones available in GIS software. However opinions may differ.