AnsweredAssumed Answered

Viewshed inconsistencies

Question asked by geonetadmin on Mar 2, 2012
Latest reply on Mar 7, 2012 by geonetadmin
Original User: kkvh5369

Hi all,
I am teaching a GIS module.  My students had to calculate a viewshed based on a single point and a DEM - all had the same datasets (downloaded from the same source) and the same license / version of ArcGIS (9.3, SP1 on an Info license - with the spatial analyst extension checked).  A few of them ended up with a totally different result to the majority (screenshots below), despite using the same data and running the tool in the same way as everyone else.  We tried re-downloading the data, in case the data was corrupt, but still the same students ended up with a different viewshed to the majority.  They have tried it on different machines (we are working on networked computers in a university).  I can't think why this would happen, and can't replicate the error on my own machine or fix it on theirs!  Any clues very gratefully received...
The attribute table of the observation point:

The "correct" viewshed (i.e. the viewshed that the vast majority of students, and I, got):

The "incorrect" viewshed (i.e. for a few students, approx. 5 out of 65):