I'm using Arcmap 10, I need to create a raster from contour lines. These contour lines were clipped out with a certain shape with the purpose to modify them only within that shape and then create the raster from these modified contour lines. The problem is that when I come to the TopoToRaster step, the resulting raster is rectangular, while I'd need it with the shape I used for the clipping. How can I do this? Should I change some options in the Spatial Analyst? How?
Before performing topo to raster, you need to add a single polygon (input) which will be your desired boundary and change type to boundary (yes there is a dropdown key there).
The Clip_management Tool will clip a Raster to a real geometry outline. It is located in the Data Management\Raster Toolset. The 6th parameter is where you define "clipping_Geometry" (polygon perimeter). The default is to clip to an extent. Perhaps you can run Clip_management after TopoToRaster.