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Node Dangles


For some odd reason, I wanted to split all the arcs in a polyline feature class to a specific length–if a specific feature was longer than the target length, it would become two or more separate polyline records. Here is the bare-bones script that copies an existing feature class into a new feature class then processes each record, splitting it into multiple records if the polyline is longer than the user-specified tolerance.
I have to often get a table structure for a feature class or table into either a spreadsheet or word processing document. There might be an easy way to do this in ArcGIS 10 but I haven’t found it. So, as is my nature, I decided to roll my own. This is a bare-bones script that iterates through the fields, printing the field name, type, width, and precision. There are three optional features to it:
I was making an edit (adding leading ‘0’s) to a coded-value domain in an SDE database and realized that my edits were changing the order of the rows of my domain. Rows were moved to the bottom of the list when they were edited. So I went through the process of converting my domain back to a table, made my edits in Access and exported the rows to a .dbf in the order I wanted them.
While I’m enjoying the functionality of the new Referenced Mosaic Dataset that have been introduced in ArcGIS10, something that I stumbled over recently was administering the privileges to a referenced mosaic dataset. A referenced mosaic dataset is a raster datatype that uses a mosaic dataset as a base. For example, we loaded a series of DEMs into a mosaic dataset and then created a referenced mosaic dataset that does the meters to feet conversion for us.
One of the things I had not gotten around to doing in ArcGIS 10 was figure out how to directly manipulate the geometry of a record using the Field Calculator. When I stumbled upon a bug in the way the Extract Values to Points tool handles Null geometries, I figured it was time to figure it out. Setting the X, Y to 0,0 was sufficient for my needs. I set the Parser to Python and the formula was simple once I figured out the syntax:
One of the Spatial Analyst tools we often use in ArcGIS is the Extract Values to Points tool. This allows us to take a point file (well locations in our case) and attach a value (elevations) from a raster image (a DEM) to each point. Today I was running it for the first time against an Image Service we recently published and I received a warning message,‘WARNING 000957: Skipping feature(s) because of NULL or EMPTY geometry’.
To better organize our ArcSDE data, we wanted to create multiple geodatabases and multiple ArcSDE services using one PostgreSQL database cluster (a cluster containing 1 machine at this point). A side question is why can’t tables and raster be placed in Feature Datasets? This wouldn’t be an end-all solution for what we want to do but there are some messy consequences of this limitation. ESRI has instructions on Setting up multiple geodatabases in one PostgreSQL database cluster on Windows which was helpful but we repeatedly got an ‘The ArcSDE Repository was unsuccessfully completed.
We finally installed an instance of ArcSDE 10 today. My first attempt at connecting in ArcCatalog 9.3.1 failed with the following error: Failed to connect to the specified server. This release of the GeoDatabase is either invalid or out of date. [Please run the ArcSDE setup utility using the -o install option.] DBMS table not found [sde.sde.GDB_Release]  Turns out the solution was simple, this article points out that Service pack 2 is required.
Since the name of the blog is Node Dangles, I get several hits daily from searches on ‘Node Dangles’ and I have no information on node dangles. This post is the first in a series to change that. First let us, by us, I mean ESRI, define what a node dangle is. Their online glossary actually defines a dangling arc, a dangling node is a node (endpoint of an arc) that does the non-connecting mentioned below:
UPDATE: After receiving a request to modify the code to ignore .lock files, I have an updated to this post. One of the tasks I’ve been automating is publishing a weekly data update to a website. The update consists of shapefile. The trouble with shapefiles is they consist of 3 or more files with the same basename but different extensions in the same directory. Not an overly complicated situation but a common one that ArcGIS does not have a solution out-of-the-box.