|
POST
|
Greetings, You can do this using the Lookup tool available with spatial analyst or 3d analyst. Regards, Eric
... View more
02-26-2012
10:21 AM
|
1
|
0
|
3496
|
|
POST
|
Mike, I see that you're working with a mosaic dataset. Is there a reason you want to output a hillshade to disk, which requires storage? You can simply add the Hillshade function to your mosaic dataset and the system will generate a hillshade on the fly. As recent as this week I outlined how to add the hillshade function to a mosaic dataset containing elevation data. You can review step by step here: http://forums.arcgis.com/threads/51137-Hillshade-coming-out-totally-wrong Regards, Eric
... View more
02-24-2012
12:12 PM
|
0
|
0
|
4678
|
|
POST
|
Did you find another way to extract from a raster using a polygon mask? Try the Clip tool. Regards, Eric
... View more
02-24-2012
12:05 PM
|
1
|
0
|
4136
|
|
POST
|
Hi Graham, Thanks for the info. It's very helpful, and we'll get you situated in no time at all. First though, I'd like to point you to some more reading. Why does my hillshade look different when I use a tool vs. a function? Given the information in the link, and the extent at which you want the hillshade to look good (zoomed out), I am going to recommend you use the Mosaic Dataset option and work with the Hillshade Function, rather than the Hillshade GP tool. We already know the tool result looks good when zoomed in. The display at smaller scales is less appealing because the Hillshade tool is applied at the source pixel size of the data, then resampled when you zoom out. For this reason, the Mosaic Dataset is better because the Hillshade function is applied at the scale in which you are viewing the imagery, first resampling the DEM to that resolution before applying the hillshade effect. Forget the mosaic's you've created so far and only work with the original source tiles in WGS_1984. I assume you are working with 90m SRTM data given your cell size of 0.00083333333. Your X,Y units are therefore Decimal Degrees. The Z unit I asked about was asking what units the elevation values were in. I'll assume elevation is expressed in meters. Workflow: Create a geodatabase and a mosaic dataset. When you create the MD, set the coordinate system to ED_1950_UTM_Zone_30N or WGS_1984_UTM_Zone_30N if you want to avoid setting a geographic transformation later. Use ED_1950 if you require it. By setting the coordinate system of the MD to something that uses meters for X and Y units, you are assuring that X,Y,Z are all in meters, simplifying the Z factor decision later. You'll just use a value of 1. Run Add Rasters to Mosaic Dataset tool. Use Raster Dataset for the Raster Type parameter. Point to the original data or the workspace where they all reside - your choice. Load the data with UNC paths rather than C:\ or some other mapped drive letter if you plan on others accessing the data. Check the box to "Update Overviews". This is how you avoid seeing the gray box at small scales. If the Mosaic Dataset is lacking statistics at this point, do not bother building them because they will only be invalidated after applying the function. Add Hillshade function In the Catalog window, right click the MD and click Properties. Click the Functions tab. Right-click the Mosaic Function and click Insert > Hillshade Function. Adjust parameters to your liking. Z factor should be 1. Click the Defaults tab when you're done with the Functions tab. Set the Default Resampling Method to Bilinear Interpolation. Also on the Defaults tab you can set the Geographic Coordinate System Transformation if you do use ED_1950. The statistics of the mosaic dataset are invalid since the original statistics were calculated on the elevation data (signed 16 bit data) and the hillshade is producing a 8-bit image. The last step is to recalculate the stats. In the Catalog window, right-click the mosaic dataset and click Calculate Statistics. When calculating the statistics for the mosaic dataset, you do not need to calculate them for every pixel. It is highly recommended you specify a skip factor. A simple equation is the number of columns divided by 1,000. If you don't specify a skip factor, this process could take a very long time. View the mosaic dataset in ArcMap and let me know what you think at varying scales. Regards, Eric
... View more
02-23-2012
10:46 AM
|
0
|
0
|
6571
|
|
POST
|
Hi Graham, The hillshade you first displayed in this thread looks fine I bet when you zoom in. True? You definitely have pryamids built on that one and maybe displaying it with nearest neighbor resampling (or even had pyramids constructed that way). Did you try deleting the pyramids and checking the display again? If we can back up for a moment we should be able to get this sorted out. What is the coordinate system of the orginal data you had, and what is the unit of the pixel (z unit) data? You want X,Y,Z to all be the same for this to work out nicely. After mosaicing the smaller tiles, did you project it? Or was the target mosaic a different coordinate system than the source tiles? How did you mosaic it basically? Projecting raster data defaults to Nearest resampling as well, so for elevation data this would be bad. You want bilinear. Also, what is your license level? I personally would just use a Mosaic Dataset in 10.0 and apply the hillshade function on the fly, rather than having to store on disk the DEM data plus a derived hillshade dataset. See Managing Elevation Data A hillshade result is 8 bit unsigned data. It can't possibly go to something like 2000+. Further, the hillshades values are not indicative of elevation as you seem to indicate should be the case. Hillshade is simply returning illumination values. The documentation indicates the valid output range is 0-255. Regards, Eric
... View more
02-22-2012
11:19 AM
|
0
|
0
|
6571
|
|
POST
|
Greetings, Point Density provides a count per unit area. To understand the output you have to understand the units of the input and the parameter called, "area_unit_scale_factor". The tool goes to a cell, looks for points in the search radius and sums them, then divides by the area of the search radius. For circular or rectangular its quite easy to confirm the results by hand. For more examples about understanding the output units, please review, How Point Density works. What are the units of the points, and what did you fill in for all the other parameter values? Regards, Eric
... View more
02-21-2012
01:57 PM
|
0
|
0
|
3948
|
|
POST
|
Hi Diann, How are you confirming the output is not the extent you specified? A visual check perhaps? Are you increasing the extent of the raster? Have you turned on NoData to display as some color so you can visually see where the extent really ends? I would also advise you to set a snap raster so all raster pixels align. Eric
... View more
02-14-2012
10:24 AM
|
0
|
0
|
9011
|
|
POST
|
Greetings, You can do this by embedding an IsNull statement within a Con statement. Con(IsNull("raster"),0, "raster") You may find these resources useful. How to add different-sized rasters with NoData Values Raster Extents + Calculator Problems Best Regards, Eric
... View more
02-13-2012
12:25 PM
|
0
|
0
|
9011
|
|
POST
|
Hi Al, It sounds like you have SRTM 90 m data, which typically comes in a geographic coordinate system (WGS_1984) having a resolution of 0.00083333333 decimal degrees. If you truly want your data to have units of meters you need to run Project Raster and specify a coordinate system that uses meters. Then you specify 250 for output cell size. Please be sure to set your resampling technique in the tool to Bilinear since the default is Nearest (which you don't want). Best Regards, Eric
... View more
02-10-2012
07:06 AM
|
0
|
0
|
4070
|
|
POST
|
Tobias, There is a tool called Sink Evaluation available with ArcHydro. I've confirmed with the ArcHydro team that it does exactly what you're asking for. ArcHydro is free and is available from the Hydro team's blog post, Arc Hydro Tools Version 2.0 Are Now Available!. Esri Support Services does not support these tools. If you encounter issues with any ArcHydro functionality, you can post in the ArcHydro Forum, or email [email protected]. Please review the documentation for the tool. It outputs a lot of information in addition to the volume calculation you're seeking. Best Regards, Eric
... View more
02-10-2012
06:42 AM
|
0
|
0
|
1602
|
|
POST
|
Hi Andy, What format (not the same as file extension) are the images? I am not familiar with raster data being stored as .iso files. Esri uses .iso files to distribute our software these days. For example, ArcGIS 10.x software is provided in the form of downloadable .iso files after login with a valid user account on the Esri Customer Care Portal. An ISO file, often called an ISO Image, is in fact an "image" of an entire DVD. After the ISO image file has been downloaded, it can be used directly from the system's hard drive as a virtual disk by using either an ISO image file extractor program to extract the files, or by using an ISO mounter program (e.g., Virtual CloneDrive). In addition, a copy can be created on physical media by using a DVD authoring program and DVD burner to burn the ISO image on DVD. Do you know who made the aerials? Best Regards, Eric
... View more
02-08-2012
06:33 AM
|
0
|
0
|
1612
|
|
POST
|
Do you have overlapping polygons? This usually leads one to unexpected results. -Eric
... View more
02-07-2012
06:28 AM
|
0
|
0
|
5138
|
|
POST
|
Greetings, Based on your description I would suggest peforming a supervised classification. This should point you in the right direction. An overview of the Multivariate toolset Regards, Eric
... View more
02-03-2012
06:21 AM
|
0
|
0
|
490
|
|
POST
|
Greetings, The input needs to be 1 or more layer files (.lyr), which store the 3D rendering properties. Regards, Eric
... View more
02-02-2012
08:03 AM
|
0
|
0
|
810
|
|
POST
|
Martha, The Near tool is only available with an ArcInfo license for Desktop. There are 3 licenses: ArcView, ArcEditor, and ArcInfo. Your post doesn't say which one you have, but that is the proper message if you indeed don't have an ArcInfo license. The Near 3D tool will of course require a license for 3D Analyst regardless of your license for ArcGIS Desktop. Every geoprocessing tool shows you the required license level in the documentation. Best Regards, Eric
... View more
01-25-2012
09:44 AM
|
0
|
0
|
1292
|
| Title | Kudos | Posted |
|---|---|---|
| 1 | 10-12-2012 03:00 PM | |
| 1 | 04-12-2011 03:29 PM | |
| 1 | 09-25-2012 07:54 AM | |
| 1 | 09-21-2012 08:56 AM | |
| 1 | 09-19-2012 11:59 AM |
| Online Status |
Offline
|
| Date Last Visited |
10-22-2021
02:45 PM
|