Latest Contributions by EricRice

These threads should get you going, but the main thing I will point out is that Spatial Analyst doesn't calculate percentages for you.  It gives you the raw counts.  You must convert to percentages.  I should also point out that if your buffers overlap you must handle this special case by looping through the features individually. http://forums.arcgis.com/threads/70779-ArcMap-Land-use-type-as-a-percentage-of-total-area?p=248229#post248229 http://forums.arcgis.com/threads/31789-Calculating-the-area-and-the-percent-of-cells-of-each-value-in-a-raster!-Automaticall?p=236867#post236867 (I have a GPK in this one that shows how to convert counts into percentages) Best, Eric ... View more

Please show us a Hillshade from that DEM.  If it is gridded like your flow direction raster then you or someone has most likely projected the data with Nearest Neighbor resampling.  If it wasn't projected, and some other resampling was done to change cell sizes, using Nearest would still cause this.  The NED FAQ has a topic on this. http://ned.usgs.gov/faq.asp#RESAMPLE If your DEM is "old" by USGS standards, then striping can be there too.  See http://ned.usgs.gov/about.asp ArcGIS doesn't cause these artifacts. Best, Eric ... View more

Interpolate Shape is the only tool mentioned so far that actually creates a 3d file.  All the others just give the point data an attribute of height acquired from the TIN/Raster.  If you don't have a PointZ file from Interpolate Shape and all you have is an attribute you can still display the points in 3d using the attribute.  On the base heights tab in the section, "Elevation from features" choose "Use a constant value or expression".  Then click the Expression Builder icon and point to the field containing the height information. Best, Eric ... View more

Just adding to Jeff's response.  There is no need to convert .img to GRID before running mosaic.  You can mosaic the .img's directly.  Best, Eric ... View more

Eric - To get the values into his original points' table, doesn't he have to do my steps 3 and 4? There isn't anything wrong with the workflow you provided since it was designed to keep/update the "original" point feature class.  However, the result of the Spatial Join would be the original point geometry and original attributes PLUS the desired attributes from the polygon layer.  Typically people discard/archive the original layer that lacks the necessary attributes and just move forward with the spatial join result which has everything. Best, Eric ... View more

All you need to do is perform a spatial join.  When you join polygons to points, the points will get the attributes of the polygon it falls inside of or is closest to (your choice). If there are a lot of fields in the polygons that you don't want transferred to the points, simply turn those fields off via the polygon properties > fields tab. Steps: Add both points and polygons to ArcMap. Right click on points > Joins and Relates > Join Select "Join data from another layer based on spatial location" from the first dropdown. Select your polygons as the layer to join to. Specify output and run it. Best, Eric ... View more

CJ, ArcMap's dataframe (right click 'layers' > properties in the TOC)  does not have to be the same coordinate system as the data in the map (the two point layers).  When you add GCS points to a map defined in UTM space the application projects the data on the fly to UTM.  This is very common in ArcGIS. A single UTM zone isn't suitable for data that covers all of Canada so I'm not sure why the dataframe is set to that rather than something more continental. For your analysis though, the dataframe coordinate system is irrelevant.  Your data is GCS and that is what the tools are going to use.  So, you must run the Project tool.  The tools is pretty basic.  Give it your input, select an output coordinate system suitable for Canada and distance analysis, define the output name/location, and set any geographic transformations if you're going to be switching datums.  Transformations are only optional if you're not switching datums. Eric ... View more

Chris, The answer is in the excerpt from above.  i.e. "you must first project your input to a projected coordinate system using the Project tool."  So, you don't really change anything on your data.  You input it into the Project tool and create a new output that uses meters for its linear unit.  Once you get the distances in meters, you can easily add another field and using the field calculator, convert the meters into kilometers. Best, Eric ... View more

Rusty, You should set -32767 as the nodata value rather than leave it as background, which is a real pixel and is included when DRA is used.  Using Set Raster Properties to define the nodata value is faster than using Copy Raster to do the same, since this tool doesn't have to copy the data. Best, Eric ... View more

You can run Reclassify using those break values.  The output raster attribute table will have a count field for each class. Best, Eric ... View more

I hope the Mosaic allow for this. Mosaic Datasets support time awareness.  See Time in a mosaic dataset Best, Eric ... View more

Hi Eric,  thanks for the info.  I was able to create a new raster catalog and mosaic dataset with New > Raster Catalog... and New > Mosaic Dataset but I don't see how to load my existing raster catalog into either.  All load/import tools are looking for datasets or raw images. Hi Bob, If you take the raster catalog approach, you have to load the source rasters again. You can't load a catalog into another catalog.  However, if you take the mosaic dataset approach you have a few options.  First, you can run Create Referenced Mosaic Dataset which creates a new mosaic dataset from an existing raster catalog, a selection set from a raster catalog, or a mosaic dataset.  You can right click on your catalog and see this option in the context menu or you can just open the tool from ArcToolbox.  Second, you can load the existing raster catalog into your new (empty) mosaic dataset by specifying 'Table' for the Raster Type parameter within Add Rasters to Mosaic Dataset. Lastly, you can load the source rasters into the new (empty) mosaic dataset using the Raster Dataset - Raster Type, or if you have sensor data and we have the matching raster type, just specify that.  See, What is a Raster Type for more information.  You will probably want to review, What is a mosaic dataset since it outlines the differences between a referenced mosaic dataset and a regular mosaic dataset.  Best, Eric ... View more

Greetings, Definitely do not project each of the individual raster datasets.  All you need to do is build a new raster catalog with the coordinate system you want.  Specifically, you want to look at the "Coordinate System for Raster Column" parameter.  The spatial reference of the raster column is used during data loading as: A default spatial reference for those raster datasets that have an unknown  spatial reference A target spatial reference if you choose to project your raster datasets  that have different spatial references from the raster column The raster catalog has been superseded by the mosaic dataset, which has  many more capabilities, uses, and functions. Therefore, it is  recommended that you manage raster data using a mosaic dataset instead  of using a raster catalog.  Mosaic datasets can be in a different coordinate system (and even datum- unlike catalogs) than the source data feeding into it. Best, Eric ... View more