Latest Contributions by DuncanHornby

What do you mean by centreline? What if you have multiple overlapping polygons, what do you envisage in that scenario? May be you should upload a sketch of what you are after? ... View more

Steve, For the benefit of others you should mark you post as answered and are encouraged to vote up or down answers/questions. Duncan ... View more

Definitely for ESRI grids but also good practise for other datasets. For example if you create a bunch of shapefiles starting with numbers then decide to import them into a geodatabase, you cannot, as geodatabases do not support tables beginning with numbers or contain spaces\weird characters. So avoid shooting yourself in the foot all the time and employ a strict, simple, naming convention backed up with simple metadata to explain the name if it gets a bit cryptic (which it can if you start generating hundreds of datasets). If you start geo-processing with crazy names then python/model builder will blow up and cause you a head ache. And they do get crazy, some "expert" consultant was sending me data with commas and superscript 2's in the dataset name... ... View more

Mark, You manipulate the extent throught the IActiveView interface. Duncan ... View more

Michael, Are you asking you want to actually see the text " YYYYMMDD HH:mm:SS UTC " as a default rather than "12:00:00 AM" or you want to see "12:00:00 AM" in the "YYYYMMDD HH:mm:SS UTC" format? From your code you create a datetime object but don't actually set any of its properties, have a look at the examples at the end of this page. Duncan ... View more

Rob, Move the line that creates the spatialfilter object out of your looping code and place it above, you only need to create this object once. So move these line above the beginning of your loop ISpatialFilter SPF = new SpatialFilter(); SPF.SpatialRel = esriSpatialRelEnum.esriSpatialRelWithin; Duncan ... View more

Upload an image of what you are trying to achieve. ... View more

Jeff, Just looked at your sample data on a machine without spatial analyst so I can't test the cell statistics tool. I did notice that your raster format is floating point. So the error you are seeing is caused by the computer not being able to store the number precisely. Your mean values are very small. If I have understood you, if you add all the cells up in a single grid then it should be exactly 1? Well I've not seen this! I went into the symbology tab > classified and clicked on classify to have a look at the SUM, none of them added up precisely to 1. This is where the issue lies. That's why none of the examples you see in Help are floating point... 😉 Duncan ... View more

Jeff, Sounds like the source of your problem could be a spatial alignment issue? You say your grids are the same extents but are they different coordinate systems? If not reproject the grid that is different so they are all the same. Also set SnapRaster environment setting to your master grid. Duncan ... View more

Compacting a Personal geoDatabase can reset as discussed here. Maybe you could export the table or have some code trigger at an appropriate value and direct the data to a new table? ... View more

David, I'm not really a raster "guru" so maybe giving you bad advice but for the record I've just tested this scenario. I created 4 constant value rasters first was 1, second was 2, third was NODATA and fourth was 3. I used the Composite Bands tool to combine them and it created a 4 band raster where the 3 band was just NODATA values, so it can be done. I just don't know what implications this would have on display or processing? Duncan ... View more

Daniel, Looking at your picture I can see that your dataset is in decimal degrees. ArcMap is assuming that your event data is also in decimal degrees hence the large offset. You either need to convert your distances in Excel into decimal degrees or reproject your spatial dataset into a coordinate system that has meter units (typically your national grid or UTM). Duncan ... View more

The attribute table of a integer raster normally has a value field (the pixel value) and a count field (the number of pixels in the raster with that value). So to see the words "open water/open space" you must have joined another table to it. The other table must have 2 fields in it: one for the pixel value and another the descriptive text (in your case a land class). So at some point you have joined this table and I guess you need to find that table or recreate it? Duncan ... View more