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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.
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10-22-2012
05:20 PM
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I have some geo referenced images that I need to extract a series of pixel values for at specific lat/long locations (that part is easy). I also need to extract the image x and y for each of these pixels and I don't see any way to do that in Arc. Any suggestions for getting the image xy (not the map xy) from an image layer based on input coordinates or points? Thanks, David
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10-22-2012
12:25 PM
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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.
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10-15-2012
08:42 AM
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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?
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10-12-2012
05:32 AM
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I'm trying to build a mosaic dataset for a collection of ASTERv2 DEMs and am running into an issue with the appearance of the mosaic. Following the instructions in the link below I calculated statistics and built pyramids for my ASTERv2 tiles before adding them t the mosaic dataset. I then created overviews so I could preview the mosaic at full scale. But when I finished the resulting mosaic looks mostly gray, as though no stats had been calculated. I've then tried to clac stats for the mosaic itself but the process never finishes. I've tried several times up to 91 hours for the longest attempt with no results. When I compare my ASTERv2 mosiac to a older ASTER mosiac we have which does look ok as a mosaic the only difference I see is that the input tiles to the older mosaic did not have statistics built first. You cans ee the difference in the attached PDF. Any idea what I need to do to get this newer version to look like the older version? Do I need to go back and remove statistics from the tiles before adding to the mosiac? http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//009t00000039000000 I appreciate the help, David
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10-09-2012
08:18 AM
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I have a student who is interested in measuring the curvature of sections of a coastline and I'm wondering if anyone has any experience with this kind of geometric calculation using ArcGIS?
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09-17-2012
03:30 PM
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I'm wondering if there is a way to populate an attribute field for a feature with that features name? I have a series of about a thousand polygons as shape-files. The attributes for each are identical, ID 0. But the names are unique, in fact each name encodes 3 attribute values for each feature. I need to merge all of these features into a single feature class but maintain the unique name for each in the new attribute table (to later be parsed into separate fields). Is there a tool or script for adding the name of a feature to its table?
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08-14-2012
10:24 AM
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are you guys using SQL, or File Geodatabases ? Sorry for slow reply. File GDB. Or we were, now using shp files.
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08-14-2012
10:15 AM
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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.
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08-08-2012
08:11 AM
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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.
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08-03-2012
08:32 AM
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Not sure if this is the correct forum for this or not. I�??m looking for some basic info on data sharing/syncing between users who need to connect to the same projects and data from remote locations? I work for a firm that houses all of is GIS data in a central location but has users who are in different offices (different states). We would like people with different projects and different locations to be able to seamlessly hit the same data without having to make local copies. We also want .mxd files to be able to be passed back and forth between remote locations while maintain its connection to the centrally located data. Initially we tried using a VPN connection between users and the data server, but arc ground to a halt on anything other than the smallest files. We have tried SugarSync with some initial success, where data folders between the remotes users are synced to the data server. After each .mxd is closed the file syncs back to the main server folder and new users can then open their synced copy locally and see the updates. Now having trouble with this connection but is likely a setup/IT issue. While we try to sort out how to get SugarSync sorkign again, I�??m looking for suggestions or examples from the forum on how you handle this type of data sharing need?
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07-27-2012
08:36 AM
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Hi, I have a student with a research problem that I need some help with. Student has a basic road network with various road classes from minor up to Interstate. He wants to create an adjacency or connectivity matrix between major nodes along the interstates, across the entire network. His goal is to assign to the major nodes the total number of connections or possible routes between them, and the sum of the vehicle capacity of all those connections. I've looked at Network Analyst and the schematics tools. I haven't worked with either before and the they don't specifically seem to do anything like this but can't be sure. Any ideas on tools or workflows to follow for this? Thanks, David
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06-22-2012
08:19 AM
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Not sure where this belongs, hope I got the right forum. I'm working for a firm where I access GIS data and .mxd files across a VPN network from one state to another. The "server" is a separate drive on a regular desktop computer that is actively used during the day, it is not a dedicated server but it is a newer machine. The connection is extremely slow to the point that map redraws will take 30 seconds where they should only take 2 or 3. Is there any basic wisdom on how to set up Arc for use in an environment where multiple users in different offices need to access the same .mxds and data? My feeling is that the server should be a dedicated machine, how important is that? or will it still be slow if using the same VPN connections and networks?
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06-15-2012
02:51 PM
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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.
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06-12-2012
08:35 AM
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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.
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06-07-2012
12:52 PM
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