Latest Contributions by ChrisDonohue__GISP

Here's a previous thread here on GeoNet on the subject that may offer some insights: ESRI Technical Certification  In terms of what it is like, I took the ArcGIS Desktop 10.1 Associate exam a few years ago and can offer some observations from that experience: The exam is very comprehensive.  Be sure to study all the topics, as you will get questions from all areas.  To find the test topics, start by checking the specific exam at https://www.esri.com/training/certification-find-exam/ and then click on "Download Preparation Resources".  Also, look at the "Skills Measured" tab and the other tabs. It is an online exam, but one does not have access to ArcGIS software.  So in some cases one has to be able to remember/visualize how some processes work without the usual cues/reminders from ArcGIS.  Chris Donohue, GISP ... View more

To build on what Dan Patterson suggested, one could create a field in the feature classes (for example, name the field LineType) and then attribute each line as either "original" or "alternate", then symbolized differently based on these two.  A layer file (.lyr) could be used to keep the symbology consistent if there are multiple feature classes.  Then for situations where you only want to display the original lines, one could use a Definition Query to limit the display.  Displaying a subset of features in a layer—Help | ArcGIS Desktop  One could copy the feature classes in the Table of Contents and have one set to show all lines and the other set with a Definition Query to just show the original lines.  Then for viewing the two potential situations, turn on one or the other. Chris Donohue, GISP ... View more

A big thank you to the ESRI staff who participate in GeoNet.  You provide another invaluable resource in helping GeoNet users educate themselves in GIS and troubleshooting issues.  I have heard that for many ESRI Staff that being on GeoNet is not a regular part of their job; thank you for going above and beyond and sharing your (unpaid) time with us. Chris Donohue, GISP ... View more

Like what Joshua Bixby suggested, the question can be read many ways, which complicates finding a solution.  Can you restate what you need in a different way so we can get a better understanding of what the goal is? As for a solution, so far it is sounding like what possibly would work is a Summarize (Modelbuilder) or its Python equivalent. Summarizing data in a table—Help | ArcGIS for Desktop   However, that is just a guess based on what most of the possible goals could be. Chris Donohue, GISP ... View more

The Compact (Data Management) geoprocessing tool also can be handy to employ as one of the side effects of its processing is that it releases locks. To keep track of locked datasets, ArcGIS places *.lock files in the file geodatabase folder. When a process terminates, the .lock files associated with it are automatically deleted. In some cases, however, such as when a process ends prematurely, .lock files may be left behind in the geodatabase folder. These .lock files are eventually removed by ArcGIS in future sessions as new locks are taken. They are also removed whenever you run the geoprocessing Compact tool or copy and paste the data in the Catalog tree. File geodatabases and locking—Help | ArcGIS Desktop  Note that the similar-sounding tool in ArcCatalog (Administration, Compact Database) does not have the same lock-releasing capability. Chris Donohue, GISP ... View more

In Raster Calculator, for the fourth condition, try using VALUE (all caps) and put the whole expression in double quotes. Example: Con("9032_75mTEST.dem", 30, "9032_75mTEST.dem", "VALUE < 30") Chris Donohue, GISP ... View more

My bad -  I just realized I didn't express correctly what the third condition is.  It's not the elevation field, but instead the filename of your source DEM.  The third condition tells the process what to do when the evaluation expression is false, which in this case we want the original elevation value to be used. I ran a quick test using the CON (Spatial Analyst) geoprocessing tool (instead of Raster Calculator), and using 30 as a value to fill to, and it worked.  Here's what it looks like. If I get a minute, I'll see if I can figure out the Raster Calculators statement. Chris Donohue, GISP ... View more

Actually, the Z-limit option performs a different function that what you were trying to use it for.  What it does is it constrains what gets "filled".  In terms of setting the pond elevations, one possibility would be to employ Raster Calculator to recalculate the lower elevations. Raster Calculator—Help | ArcGIS for Desktop  Conditional Evaluation (CON) Con (in_conditional_raster, in_true_raster_or_constant, {in_false_raster_or_constant}, {where_clause}) Con—Help | ArcGIS for Desktop  So in Raster Calculator, it would be something like this: CON (DEM filename, 1079, elevation field, elevation field <1079) Caveat - the tricky part will be if there are other parts of the DEM that are below an elevation of 1079 meters, as this universal CON statement will modify those too.  If that is the case, you will need to select just the cells that need to be modified (the pond cells) and then apply the CON statement to only them. Chris Donohue, GISP ... View more

If the suggestion by  Dan Patterson to use Snap Pour Point didn't pan out, I'd go back and carefully review the project data.  There can be many potential things that can go awry with this type of analysis.  Here's some things to look into: Is the data projected?  It is strongly suggested that all the data be in the same projection/coordinate system. Instead of using shapefiles, try using File Geodatabase feature classes in a Feature Dataset with the project/coordinate system set.  This will help keep the data consistent. Manually review all the outputs of each process step and see if they make sense.  It just takes one output being done incorrectly to throw the whole process, and for some of the outputs it will not immediately be obvious if it is wrong. Note that some of the tools in this process use thresholds.  It may take experimenting with various threshold values to find one that most effectively reflects the situation. For example, if the data does seem correct, run the Basin (Spatial Analyst) geoprocessing tool on the Flow Direction Raster.  If the resulting basins are correctly being shown, then that suggests the Pour Point is probably the issue.  However, if the Basins are not correctly delineated, then the data processing up to that step is off in some way. Also, my general advice to pass on regarding the hydrologic tools and the iteration/troubleshooting/reviewing is that what you are experiencing is pretty typical.  Even after having done this process many times, I still find it is an iterative process that takes some time and many runs, and far less often an immediate "1-2-3 OK done" process. Chris Donohue, GISP ... View more

If the above doesn't work, one aspect you may want to evaluate is whether the Datum has been incorrectly assigned to one of the data files.  What you are running into sounds a lot like a common issue encountered here in the United States, where two popular datums are used:  North American Datum 1927 (NAD 1927) and North American Datum 1983.  When one dataset is assigned the wrong datum (say it was assigned NAD 1983 when it really is NAD 1927), this manifests itself when the data is brought into ArcMap as one dataset being off from the other by several hundred feet.  After seeing this often one often instantly recognizes the issue, as their is a distinct directional shift (here in California things shift between the two on a East-North-East and West-South-West orientation). Chris Donohue, GISP ... View more

According to ESRI ArcGIS for Personal Use comes with ArcGIS Pro. ArcGIS for Personal Use Program | ArcGIS for Desktop Advanced for Personal Use  However, it may be that you have instead a Student license authorization.  The contents of that may vary depending upon your educational institution and for what class it is related to.  As to whether it comes with ArcGIS Pro, that is harder to say.  It seems like the most recent one comes with ArcGIS Pro, but if you received the software a while ago or for example with a book or Tutorial published a few years ago it may not have it. Esri Software for Students at Institutions with a Site License  ArcGIS for Student Use Program | ArcGIS for Desktop Advanced for Student Use  Can you check to see what the exact name is for the license authorization?  In other words, what product does it say it is.  If the software authorization is through a school, you may have to check with the school/program that granted it to you for the particulars. Chris Donohue, GISP ... View more

Can you elaborate on what you mean by "custom points"? Typically the Watershed tool is run based on the Pour Point, which represents the point to derive the watershed upstream from.  As an input, the Pour Point is most commonly a point in a point feature class. The outlet, or pour point, is the point on the surface at which water flows out of an area. It is the lowest point along the boundary of a watershed. How Watershed works—Help | ArcGIS Desktop  So in the Watershed Tool, for "Input raster or feature pour point data" one typically uses a point feature class with the pour point. Chris Donohue, GISP ... View more

I've not run ArcHydro myself, so someone else will have to comment on how it is done with that particular software, but if you have the Spatial Analyst extension and ArcGIS Desktop you can derive a Watershed boundary using the Watershed geoprocessing tool, preceded by several processes to set it up. Source:  Deriving runoff characteristics—Help | ArcGIS for Desktop  An overview of the Hydrology toolset—Help | ArcGIS for Desktop  How Watershed works—Help | ArcGIS for Desktop  Caveat - before one can derive the Watershed, one typically needs to do preparation on the Digital Elevation Model (DEM) to make it hydrologically correct.  The DEM will need to be processed to make it "Depressionless".  If not, there will be all sorts of wierdness.  Creating a depressionless DEM—Help | ArcGIS for Desktop  Chris Donohue, GISP ... View more

COM is short for for Component Object Model.  It's essentially a chunk of programming that can be reused for several things.  It's not a GIS-specific term, but a programming one. COM: Component Object Model Technologies  As to how it applies to the issue you are experiencing, what may have happened is that the .COM file that HEC-GeoHMS is trying to access is no longer located where HEC-GeoHMS is expecting it to be, thus the error.  If that is the case, one possible solution may be to find out which application provides the .COM file it is trying to access and reinstall it.  I don't know if that means one would have to reinstall HEC-GeoHMS, ArcGIS, or a different application, though, to get the file back where it belongs. Chris Donohue, GISP ... View more