I'm an experienced R user new to GIS, but finding my way. I've recently run into an issue that I haven't been able to find any satisfactory documentation on (but could just be searching poorly). I'm attempting to extract data from a geotiff. However, when I load said file, all I can get are color values. For example:
aMap <- raster("./tiff/mymap.tiff") extract(aMap, areaCoords, buffer=2000) []  247 247 240 247 240 247 247 247 247 247 240 240 240 247 247 247 240 240 247  247
where areaCoords is a spatial points data frame. I'm using the sp and raster libraries. Now, I can add a layer argument to raster, and get other channels (I'm assuming this goes in RGB order), but, the data is a single value in different units alltogether.
1) Is there something I'm missing in loading in a geotiff for getting data rather than just colors?
2) If all there is to extract are colors, any suggestions on converting from colors to a known scale (e.g., perhaps I can get the RGB of the low and high values of the scale - perhaps).