Land/Water pixels

Jul 6, 2013 at 3:18 PM
Edited Jul 6, 2013 at 3:20 PM
Hello everyone:

I'm starting with DotSpatial, so maybe this questions is easy to answer for you. I'm processing satellite images (size aproximate 3072 x 4064). I have a matrix with the latitude and longitude values. I'm trying to use a shape file to identify land/water pixel. I have used the <DotSpatial.Topology.IGeometry.Intersects> funtion, but due to the amount of pixel, the time to complete the process is very slow, this is reasonable because I think that the function was developed with an other purpose.

I was reading something to convert the shape to a raster image, and then use the function <inraster>.

¿Do you recomend this way to identify land/water pixel?. I was thinking to convert the shape file to raster and then use the function <inraster>, but I'm a bit confused.
Is possible obtain the color of a pixel in a map image obtained from a latitude/longitude coordinate, maybe trough this I can distinguish between by the color the land and water pixel.

Thanks very much for your time