Aspect algorithm for cells at the edge of raster??

Discussion created by matoretta on Jan 6, 2011
Latest reply on Jan 9, 2011 by matoretta
hi I need compute Aspect without using Aspect Tool in ArcMap i use algorithm which is in help..  but question is how can i compute aspect at the edge of the raster where is impossible create matrix 3x3? (or if there is some noData in matrix)  At the bottom of help there is example how to compute aspect for center cell in matrix  3 x 3. but i dont´t understand how algorithm works for others cells.. do you have any idea??  thanks a lot.