Latest Contributions by DuncanHornby

Are you saying the vertices of the polygon contain z values? You could convert your polygon to points with z values then convert these to pixels with their z values. ... View more

Iraklis, There is a geo-processing tool called Polygon to Raster  and its found in the Conversion > To Raster toolbox. Duncan ... View more

If you look at the help on this geoprocessing tool it says: The CONVEX_HULL, CIRCLE, and ENVELOPE options are only available with an ArcInfo license. Are you using ArcInfo? ... View more

Jarek, I think its to do with correct topology of the polygon. If you look at the Help on the Check Geometry tool it mentions what direction an outer ring a polygon should be. I guess when you copy the polygon into the polyline featureclass ArcMap is enforcing correct topology for the polygon and consequently your polyline ends up clockwise. Well thats my guess of whats going on... Duncan ... View more

James, Is your point data "stacked", i.e. you have lots of points that have the same XY coordinates? I think the tool ignores stacked points so may be this is reducing your dataset to less than 10? Also (not sure about this) may be you have set the output cellsize tool large and eveything falls within one cell? Duncan ... View more

David, Can you zip up some sample data that it fails on for others to review? Duncan ... View more

Just a guess here, but could it be possible that the feature to polygon tool is generating a Feature Class that contains no data?  A newer geodatabase will support a higher level of precision and so none of your polylines form polygons, whilst an older geodatabase has a lower level of precision and everything "snaps" to form enclosed areas? Duncan ... View more

David, So let me get this straight. At some point your model generates 2 layers each containing 1 polygon and you are using the spatial join tool on these? Have you tried to use the spatial join tool on these layers only (so not part of any model) to see what happens? If these polygons are not top secret maybe you can zip them up and post on this thread? Duncan ... View more

Neil, I had a play with the eval() function and was able to replicate the issue you have. For what it's worth I couldn't work out how to get it to call the function, it must be quirk of VBA in ArcMap. Duncan ... View more

Neil, I've never been able to find information about the underlying algorithms used by ESRI geoprocessing tools. Unless they are misbehaving, who cares how they do it as long as they are fast and accurate? As I understand your initial description you have 1 shapefile with a single polyline in it and you are trying to find the intersection points in many polygon shapefiles, is this correct? If so how many shapefiles are you talking about? You could consider using in_memory layers if you are generating a few layers with a few points as a way of speeding things up? Duncan ... View more

Roger, I just tried the following code on a river network I have and it did not produce an error. # Layer name in Map Document s = "Rivers" # Describe object and print name string to confirm it worked desc = arcpy.Describe(s) print desc.namestring # Get spatial reference and print name sr = desc.spatialreference print sr.name # Get FeatureClass and check if M aware fc = desc.featureclass print fc.hasm # Set M domain sr.setmdomain( -1000,1000) This would suggest that there is something odd with your layer as your code looks sound? Duncan ... View more

Why don't you call the Intersect Tool via the IGeoProcessor to create all intersection points in one hit rather than looping with a spatial filter? If you need attribute information say from the polyline dataset you could then call the spatial join tool? Duncan ... View more

Johan, Check out the HYDROSHEDS website. Duncan ... View more

Claire, Once you have converted your RAW lidar data into a DEM you'll need to fill in sinks before you create the flow accumulation and flow direction grids. I don't have ArcHydro currently installed but I remember it has a fairly comprehensive Help document to guide you. For a high level step by step guide of how to generate watersheds have a look at this section of the ESRI help. Duncan ... View more

Have you looked at the ArcScripts website? Look at this, it may need tweaking to get it working as it is for an earlier version of ArcView, or it may just work, I've not tried it. http://arcscripts.esri.com/details.asp?dbid=15877 Duncan ... View more