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Frequently Asked Geoprocessing Questions

Quick answers of some questions frequently sent to us or asked on the user forums.

The answers are using ET GeoWizards or ET GeoTools solutions and require ArcView license only.

Q: How to get the numbers of street intersections?

Q: I am trying to create a point at each intersection in New York City from the street polyline file. Does anyone know how to do this?

Q: What we need is a point layer that we can use to generate a street intersection list report. Any ideas?

Q: I need to take a street centerline shape file, and create an intersection table from it. The resulting table should contain the names of the streets, and the coordinates of each intersection.

A: Use the Export Nodes function of ET GeoWizards with the "Regular" option. This will produce a point dataset where only 3 or more street segments meat. The number of points in the output dataset will represent the number of intersections in the output dataset.

  • If you consider a street intersection the location where is a change of street name, you can include the "Pseudo" nodes together with the "Regular" nodes.
  • If you need the names of the streets at each intersection, specify the street name field in the input.
  • If you want to get the coordinates of each intersection you can use the Point Coordinates tool of ET GeoWizards .
Q: I have fantastic elevation data, much better than any DEM I can order from the USGS site, and ideally I would like to convert this data to a TIN. There's one problem, however; the data is in the form of a (CAD) topo map. The topo map consists of contour lines, and elevation values overlaying those contours (there is a break in the contour line where a value exists).

Q: I have an imported file of AutoCAD generated attributed contour lines that I'm trying to clean. There are breaks in the polylines where annotation originally was to be placed. Of course, these breaks need to be removed and the polylines with similar attributes joined. 

A: The Clean Contour Gaps function of ET GeoWizards should solve this.

Q: I have a shapefile with about 150 lines. I need to create a series of lines that are perpendicular to these lines, every 1000m. Does anyone know a quick way to do this?

Q: I want to draw polylines perpendicular to (and on both sides of) a baseline (it's a river centerline, so it is not straight) at a specified interval. I have seen a lot of discussion about this that involves coding, however I unfortunately don't know anything about coding but would like to figure out a way to do this because I have a couple hundred of them. Does anyone know a way - or could point me to a technical paper or something so that I could figure it out? 

A: The Create Station Lines function of ET GeoWizards allows you to draw perpendicular lines to the input polyline dataset at user specified distance. The user can select the side of the perpendiculars (Left, Right or Both) and the length of the perpendiculars. If the source has Z or M values the length of the perpendiculars can be taken from the Z(M) value of the source polyline at the current station.

Q: I'm trying to split a polygon into smaller polygons (parcels) of a known area (2 acre parcels). Is their any way I can do this or, as I'm cutting the polygon, to get a reading of the area of the new polygon before I finish cutting it? I'm basically subdividing a large lot into 2 acre lots and I'd rather not do it by eye or constantly readjust the size of each one.

Q: What I am looking for is some code or a method for splitting a parcel in two, based on an area. The method needs to take into account that a parcel may be of any shape, orientation or size so a basic split is not what I am looking for. 

A: While there are indefinite number of solution for the problem, the Split Polygon By Area tool of ET GeoTools offers a simplified solution by splitting the polygons with horizontal or vertical line based on user specified target area (or percentage of the total area of the original polygon) and a side (East, West, South or North) to get the sub-polygon.

Q: I am trying to figure out how to display pseudo and dangling nodes from a street coverage in ArcMap.
I can't seem to find a function in ArcGIS that lets you display them like in ArcInfo

A: Use the Export Nodes function of ET GeoWizards or Draw Nodes tool of ET GeoTools

Q: I have a coverage of storm water assets that we are migrating to Geodatabase, but I am having problems with finding a solution for one part of this conversion. In the original data there was a from and to node field but the layer will continue to have updates with new developments or road widening. So how would I get the from and to node ids in a shapefile or feature class so we can join tables and copy over our unique structure IDs to the attached pipe? 

A: Use the Renode function of ET GeoWizards

Q: How do I join two separate polylines? Something like MERGE would work, except I only want it to join the two polylines if their endpoints are "snapped" together.

Is a way to merge a group of polylines into one line. What i have is a hydro streams layer for a county where a polyline breaks at every intersection. and the streams are broken into categories of primary, secondary, and tertiary. I need to remove the tertiary streams but that leaves me with breaks in the stream segments where the tertiary streams would intersect. so does anyone know if there is a way to automatically merge all the segments that should no longer be broken. almost like a reverse planarize of lines command.

Q: I want to edit arcs in a street coverage, shapefile, and/or database feature. I don't know how to unsplit two arcs. I want to remove a pseudo-node that is no longer necessary. Right now I'm converting my database features to a coverage and going in with Workstation ArcEdit to perform unsplit.

A: Use the Clean Pseudo Nodes function of ET GeoWizards or the Clean Pseudo Nodes tool of ET GeoTools

Q: Does anybody know how to detect small gaps between polygons and holes in polygons in a feature class and store them in another feature class?

Q: I have a large shapefile that has multiple polygons (each has a different value) and I need to close the gaps between the polygons.

A: Use the Clean Gaps function of ET GeoWizards,  Draw Gaps or Fill Gaps tools of ET GeoTools

Q: Can you create polygons from lines in ArcView  using the topology tools?

A: No, but you can with the Build Polygons function of ET GeoWizards.

Q: I have created a water service points.shp (with a triangle for the symbol). I am trying to rotate these points based on there service access street, rather then manually rotating each one. Is there some way to rotate the apex of the triangle to point to the access street based on a joined database.

A: Use the Point Angle and Position function of ET GeoWizards. It will assign to each point the angle of the closest polyline segment. Then you can use this angle to rotate the point symbol.

Q: Is there a process where I can consolidate my data points to reduce the amount of points on ArcMap?

Q: Does anyone have a method of snapping points within a certain distance of each other to a single location?

A: Check the Thin/Generalize Points function of ET GeoWizards.

Q: I need to create a centerline from a river polyline coverage. I discovered that the "collapse dual lines to centerline" tool only works on uniform casings, like roads. Is there a similar tool or method to generate centerlines for rivers/ hydro features?

A: Check the Create Centerlines function of ET GeoWizards

Q: I am trying to calculate the length of sides of the polygons in the layer that are along the roadway (centerlines). I do not need the perimeter of each polygon, just the length of the sides of polygons that are along roads.

A: See this article

Check ET GeoWizards User Guide 

Check ET GeoTools User Guide.

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