392 reputation
39
bio website peterstensmyr.com
location Sydney, Australia
age 34
visits member for 3 years, 5 months
seen Mar 28 at 11:05

I mostly code in Python. Do a lot of spatial analysis and other GIS work. Some Django and a tiny bit of JS front-end stuff. Have done a lot of number-crunching in Fortran. I work with hydrology and flood modelling.


Mar
17
comment Overlay polygons on raster in different projections
Thanks for all the good points, really helpful. I am creating the raster myself as well, so I have the option of reprojecting the points to a projected coordinate system before interpolating the raster, and I want to know if this would be a "better" result or just a "slightly different" one. My original data is points in latlong (near Brisbane actually!) but within a small enough area that I could use MGA56. It sounds like this would not give a better result and I can stick with latlong.
Mar
17
comment Overlay polygons on raster in different projections
So the cells change ever so slightly? I can see that the reprojected raster does not overlap exactly with the original, while the reprojected vector does. My theory is that this affects which cells are considered to be inside the polygon by the overlay algorithm. For the case I'm comparing, the polygons are fairly small compared to the grid size (5-6 grid cells per polygon), which might increase the effect.
May
21
comment Python to get ids from shp dont return all records
@user1573901: no problem! Please consider accepting the answer (click the tick mark under the down arrow) if it solved your problem.
Apr
17
comment Why do ECWs go missing when exporting MXD to PDF with ArcPy?
Thanks, I suspected it was a memory issue. This is good for explaining, but I still don't understand why it happens externally but not within ArcGIS.
Jan
30
comment How do I get the pixel value of a GDAL raster under an OGR point without NumPy?
This is amazing. Thanks!
Jan
18
comment how to overlay shapefile and raster?
I went with this approach, though the function name is actually "Grid Statistics for Polygons".
Jul
25
comment How to perform a table look-up using Python in ArcGIS 10.0?
I would guess you have work restrictions preventing you from upgrading to 10.1? If not, just do the upgrade, it's free and surprisingly painless.
Jul
25
comment List Elements or Datasets of a given Layer
MakeFeatureLayer_management imports shapefiles to layers. If you already have a layer file, use arcpy.mapping.Layer("path_to_layer_file") to create the layer object.
Jul
25
comment Can you create labels based on an attribute field in a shapefile with Arcpy?
this needs layer.showLabels = True before the mxd.save().
Feb
26
comment Selecting points not snapped
A problem came up today and this technique was the perfect way to go through and fix it. So big thanks!
Jan
12
comment Selecting points not snapped
this is quite cool. thanks for the tip, very useful!
Jan
10
comment Selecting points not snapped
Exactly the answer that I wanted. Thanks!