Changing the shape of prediction map

Discussion created by thomazz on Jan 24, 2011
Latest reply on Jan 25, 2011 by thomazz

I have created a prediction map that shows the concentration of cadmium contamination in a Belgian region called the Campine. As can be seen in the image attached in his topic, the prediction area has the shape of a rectangle. However, I would like to change its shape to the outer frontiers of the 5 municipalities that can be seen on the image attached. I've tried to change to this shape by the option "select by attributes", but then the kriging layer does not appear.

Is there anybody who can help me solve this problem?

Many thanks in advance!