Hi OFT, I am trying to develop a form that will survey of particular forest area and the forest user group territory. It would be worthy when user can get instant area he/she surveyed and make decision instantly with forest user group.I want to calculate the area in collect mobile (SRS system will be projected). For this I need to calculate x1 * y2. I thought it will be easier using idm:position() or idm:index() function but I was wrong. Now things are being messy. How can be done such type of calculation? or is their any solution to calculate area using vertices?
Accepted answer
I solved one issue: x1*y2 using expression (location/@x(parent()/coordinate[idm:position($this/parent()) -1]/location/@y))-(location/@y(parent()/coordinate[idm:position($this/parent()) - 1]/location/@x)) Apply when idm:position($this/parent()) = 1 expression (location/@x(parent()/coordinate[idm:position($this/parent()) -1]/location/@y))-(location/@y(parent()/coordinate[idm:position($this/parent()) - 1]/location/@x)) Apply when idm:position($this/parent()) !=1. probably my apply when condition is not ok, I am not sure. I checked in excel everything is right. Now my problem is that I want same calculation as above but that would be with last and first position of the coordinate. How can I perform that work?