Latest Contributions by EricRice

Dan, The link is working for me for some reason...That is how I knew his syntax was correct. Eric ... View more

Julia, Did you select the graphic?  It doesn't matter if the polygon layer is selected.  You can use the Select Elements button to make selections on graphics. Eric ... View more

Jamal, What is happening when you click OK on the tool?  Adding two rasters together is basic functionality and is working correctly from my tests.  I just added a floating point raster to an integer raster just like you're attempting to do.  Your syntax is correct, so you need to elaborate on what's going on. Eric ... View more

I have access to both ArcView and ArcInfo levels of 9.3, along with Spatial Analyst.  We are in the process of getting ArcGIS 10, but it has not been rolled out by our IT department.  I do have access to a machine with 10, but I can't heavily rely on it yet, so the new mosaic dataset isn't a solution quite yet. Eric, I tested the formula you gave me, and it produces results that are almost idential to what the Export Dialog produces.  The only differences are from rounding because the export dialog produced an 8bit unsigned integer tiff and therefore cannot contain decimals.  That leads me to believe that the Export Dialog does in fact rescale the imagery correctly. Stephanie, Carrie and I have been doing some testing and in 10.0 and in 10.1 we are not getting results from Data Export that are the result of the formula.  We did not test 9.3 though.  If I can back up for one second to clear the 'screenshot' comment up - For single band data like an elevation layer, the Use Renderer option is essentially the 'screenshot' I mentioned.  For multiband, the image is in 8 bit space for monitor display, which is why you get an 8 bit output when choosing that option- and no it is not a 'screenshot'.  Very sorry for confusing that earlier. I'm interested in knowing what bands are displayed at the time of export.  What stretch is being used?   What sensor did this data come from?  Carrie and I have been testing WorldView2 data.  If you haven't already exported your rasters manually, please see my comment above (to Suzanne) for how to do it in batch.  Since you're on 9.3, Python is your route (See SOMA tool) since the raster calculator is not a geoprocessing tool in that version. Best Regards, Eric ... View more

Suzanne, You can use Python scripting and/or the Raster Calculator to perform map algebra.  For multiband data you must do the math on each band then recomposite them back into a new multiband raster using the Composite Bands tool.  If you can wait for 10.1 (tentatively shipping June 7th) you can just run the Copy Raster tool in a loop using the new option "Scale Pixel Values". Best, Eric ... View more

Chloe, A USGS .dem file does not need to be converted to GRID format for use in ArcGIS.  We read .dem files directly.  Just open ArcScene and navigate to the raster and add it using the Add Data button.  You probably will have to calculate statistics on the dataset before you can use it.  Once it is in ArcScene, open the layer properties and go to the Base Heights tab.  Set the layer to have its heights based on itself.  Also, the data is most likely using a geographic coordinate system.  I recommend projecting it into a projected coordinate system appropriate for the area to ensure that the X, Y, and Z values are all in the same unit of measure (feet/meters).  If you do not want to project the data (use bilinear resampling if you do) you will have to set the vertical exaggeration in ArcScene to a really small number like 0.0003 for example, to account for the fact that your X,Y are in decimal degrees and your Z's are in feet/meters. Eric ... View more

I doubt you would be interested in the area of NoData, so for the most part I would avoid calculating it.  I also want to point out that rows*columns*area of the cell, does not return 'surface area' in the way we use that term.  That formula is giving you the 2d area of the extent.  Surface area can be calculated in ArcGIS though using Add Surface Information or Surface Volume tools.  Zonal Geometry can be used to get 2d area of each zone in a dataset.  It sounds like you want the area of the 'real' pixels though, so you can multiply any raster by 0 and Int it, like I showed you and then put it into this tool.  Because it is a constant of 0, it would be considered 1 zone.  Technically, you could just convert the raster of 0 to polygon and get area that way.  I don't anticipate enhancing the Get Raster Properties tool in a way that would distinguish NoData pixels from valid pixels in terms of returning a count.  There are other methods for that.  We can consider returning total pixels based on col/row counts. ... View more

Jamal, What is the real requirement?  Do you need the count of all pixels, or just the ones with data?  These numbers can be very different as you have seen.  Why do you need the counts?  Please elaborate in detail. Thanks, Eric ... View more

Get Raster Properties tool doesn't give you the product of COLUMNCOUNT and ROWCOUNT.  We should probably just enhance that tool to provide TOTAL_PIXEL_COUNT.  It's still currently up to you to do the math, hence my comment "Not out of the box". ... View more

Please follow the knowledge base article I'm linking to and let us know if it resolves the issue with extra classes.  Do not change missing values to NoData. HowTo:  Compute the histogram with all the unique values, when using the classified renderer The Reclassify tool relies on the same histogram calculation. Regards, Eric ... View more

Not out of the box. ... View more

That raster is floating point.  You must have an integer raster to build attribute tables. Eric ... View more

Is this valid in case of the attribute tables of feature classes (point, polyline, polygon)? What about their maximum number of records and columns that they can take? Yes, it is valid for feature classes since they use ObjectID too.  For additional details on geodatabase limits you can review File geodatabase size and name limits ... View more

Jamal, The zone we created only surrounds the real pixels.  It isn't including the NoData pixels in the count.  The input value raster is 897*563, which is 505,011 pixels.  The count field you got indicates there is only 343,809 pixels.  I ran this in the raster calculator - Con(IsNull("RainfallVolume"),1) which converts NoData to 1.  I checked the count and it is 161,202.  343,809 + 161,202 = 505,011. Regards, Eric ... View more