Latest Contributions by DavidMedeiros

I actually do know how to extract values to points. What I am after is the corresponding image x/y coordinates (pixel xy in the image, not geographic xy), that go with the lat/long points. The student I'm working with needs the image xy to use in a separate script he's written that analyzes the pixel values for cloud cover and radiance at specified locations. It's not a GIS script so it just needs image coordinates for the pixels. I think I have a workaround but would still like to know if Arc can determine the image coordinates of a point over the image. ... View more

In ArcCatalog, go to Customize > ArcCatalog Options > Raster tab > Raster Layer tab.  What is your stretch and resampling set to there? Also, you can speed up the calculation of statistics by specifying a skip factor in the Calculate Statistics tool.  This will give you a generalization of the statistics. I ran the clac stats tool with a skip factor (100 and then 50). The tool ran much faster (5 - 15 minutes), and although it seemed to finish successfully, there was still no change in how the mosaic previews and the statistics fields under Properties is still blank. ... View more

Thanks Jake, I'll give that a try for ArcMAP.  My problem is that what I really want is for students who are going to be evaluating the data in ArcCatalog to see the higher contrast images in the ArcCatalog Preview tab as well. That's why I was using the calc stats. I think it took overnight, maybe 6-7 hours, to calc stats on the individual tiles in the mosaic, so I can't image it would take longer than 91 hours for the mosaic itself but maybe it's trying to do it to all of the overviews as well. I'm guessing it has something to do with the order I'm applying the overviews, stats, pyramids etc. And from looking at the original ASTER mosaic I have I can see that while stats were successfully built for the mosaic, they were not done for the tiles. So maybe I need to remove them from tiles first. Hi David, Depending on the amount and size of imagery that makes up your mosaic dataset, building statistics can take a long time.  To see features in some images or raster datasets, or to distinguish  them more easily from the surroundings, you may want to alter the  stretch applied to the histogram. In many cases, you can get the  enhancement you need by stretching based only on the pixel values within  the display and not using all the pixels in the raster dataset. This is  a dynamic range adjustment (DRA).  Try the following: 1.  In ArcMap, go to Windows > Image Analysis 2.  In the Image Analysis window, select the mosaic dataset, check DRA, and set the stretch to 'Std-dev' and resampling to 'Nearest Neighbor' Does this improve the display of your mosaic dataset? ... View more

are you guys using SQL, or File Geodatabases ? Sorry for slow reply. File GDB. Or we were, now using shp files. ... View more

are you still having a issue with this ? Sort of. We are working with Google Drive now which seems to be more stable than SugarSync was. Our only issue is not being able to use a geodatabase in the sync folder. We're contact ESRI support to see if we can figure out what the issue might be. Still looking for examples of other organizations working with remote users and a central server though. ... View more

No one else works like this, really? Well, here's a quick update to our situation. We are now testing Google Drive, which seems to work fairly well although it has some glitches associated with sharing a File Geodatabase across the synced folder, which means we'll be using shape-files instead. I'm still looking for any insight to how other companies may be handling similar situations.  Thanks. ... View more

I'm with the perceptive Mr. Quinn. You need to be very careful with .xls and .txt tables that they follows Microsoft Jet/.shp/.dbf file naming limitations: No tables or field names starting with a number, no spaces, no special characters (except "_"), short (10-chars). To avoid trouble, I try to follow these rules with all datasets. You can always be more creative with field aliases and layer names, but the datasets themselves should use "safe" names. If you do that, field names are also less likely to be garbled if the geoprocessing workflow goes through  .shp or .dbf formats. If you violate these rules, the tabular data may be read okay, but joins are not likely to work. As for the Copy Features tool, I believe it's a it's a much more useful method than data/export, since when you want to do it again (say after you change the underlying data), you don't need to go wandering through the interface, you can instead pull the Copy Features out of Geoprocessing results and re-run it. The Copy Features tool also is guaranteed to honor the specified environment settings for Current Workspace and Qualified Field Names. Just wanted to get back to this after having reviewed the input table. As far as I can see, no special characters, no numbers first, no spaces etc. I always follow the same rules but hadn't specifically checked this students table so wasn't sure. It may just be a bad table creation process leading to some underlying issue with the table itself. Although I can't see how it would successfully join to a layer but not export. As for exporting dynamic joins and selections, I typically use the data>export method because its right there on the layer. For the researches and academics I work with the contextual right click tools are often easier to find than toolbox tools and it fits their one-off work processes better I think. That said, the Copy Features tool obviously works better with iffy table joins so maybe I need to switch to that tool right away. ... View more

That is indeed the usual approach. I was simply offering another approach, since the first appeared to be giving mixed results. I appreciate the help, my exasperation wasn't pointed at you. I'm frustrated with the software! For a workaround using the copy features tool seemed to work ok and requires less manual work than the method above but its good to have multiple solutions. But I really need to understand the underlying issue and how to resolve it not just for this student but for future ones as well. I work with dozens of students a quarter here and rely heavily on this function to make permanent copies of their analysis results and table joins and I can't be resorting to workarounds for such a basic function all the time. ... View more