My question is about how coordinate systems affect comparison of different layers - I have tried to refresh my memory about coordinate systems in GIS, but am still unsure about this situation.
I am comparing the land cover classifications (estimates of the % each land cover type represents in the given area) from a raster layer versus from a vector shape used in photo-interpretation. This comparison will be done on many raster-classification/photo-interpretation combinations throughout the United States.
The area of the vector layer comes from delineating a watershed (generally 25 to 250 square kilometers in area), and that delineation and vector layer is then used to clip that area out of a larger land classification raster layer.
The vector layers used in photo-interpretation are all in lat/long (unprojected). The photo-interpretation is already done, so I need to keep these source shapes as they are. These vector layers have the following coordinate system:
Geographic Coordinate System: GCS_North_American_1983 Datum: D_North_American_1983
All of the raster layers I'm working with have the following coordinate system:
Spatial Reference: Albers_Conical_Equal_Area Datum: D_North_American_1983
Are the areas of these 2 GIS layers the same, given they have the same Geographic Coordinate System, or am I in error to compare the vector layer to the raster layer, given that the vector layer is not projected and the raster layer is? If the latter, then can I simply project the vector layer to the same coordinate system as the vector layer, and if so can that be done after clipping the raster to the vector shape or must the projection be done before clipping?