3d Analyst: controlling Z units of ViewShed or manipulation

[yonatanrubinstein]

Hello,

I did a Viewshed from a point feature (using a DEM), but I would like to do it again but by "correcting" the point feature elevation by 90 meters.

In Line of sight, I can adjust the point feature elevation by entering "Z-units". In Viewshed, as far as I understand, the value that is entered in the Z-units is multiplied in the DEM, not changing the viewshed at all.

Does anybody know how can I do the viewshed for a higher elevation than was is recorded in the DEM, or must I manipulate the DEM for that?

Second question: How can I manipulate the DEM for the point element only?

(technical stuff: I'm using ARCGIS 9.3.1 with a metric prj)

[DavidLock]

Hi Rubin

You need to use the attributes within the point shapefile OffsetA (as a double) field sets the height of the point, OffsetB (double again) sets the observer height (usually 2m for people looking) and then theres ways to limit radius and angles of view etc.. its all in help under viewshed somewhere...

regards

David

[yonatanrubinstein]

Thanks David.

I Guess the help wasn't clear enough when I read it in the first time. This way (PUTTING PARAMETER VALUES IN THE POINT FEATURE ATTRIBUTE TABLE) isn't very user-friendly (As it forces me to make a different feature class for each scenario), and didn't work at first (I tried three times and all the results were not correct (I compaired it to the Line-Of-sight)), but at last it worked now.

Thanks a million.