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Creating a Velocity Contour Map using vectors with ArcGIS?

December 09 2009 | 0 comments
Categories: Map Data

I was able to create ice flow velocity vector arrows with ArcGIS from pairs of GPS points I measured on a glacier I am researching. I have approximately 40 vector arrows created through the process listed you explained to me below. Now my goal is to use ArcGIS Spatial Analyst to create a velocity contour map with the ice flow vectors. How do I do this?

Thanks so much!

Seth

ORIGINAL EMAIL FROM ESRI MAPPING CENTER REGARDING "MAKING A VECTOR MAP" BELOW:

MY QUESTION:
I am attempting to make a vector map of ice flow on a glacier using ArcView.
I have approximately 40 GPS point locations on a glacier and I know the distance the ice travels per year and azimuth of ice flow movement for each of the points. In other words I have a length and direction beginning at each point if I want my vector arrows to be displayed in distance/year.
Any idea on the process of creating a vector map with arrows in ArcGIS 9.3?
Beyond a simple vector map I hope to use this data to grid my research area and make a velocity contour map eventually.

ESRI ANSWER:
Since there are only 40 points, using the editor would be easiest and most direct.

First create a new line feature class in ArcCatalog--you will be adding your vectors to this.

Second, add your points and your empty line feature class to a new ArcMap session, show the Editor toolbar, and start editing:
* Set the snapping environment to snap to your points.
* Use the Identify tool, and click on the first point that you will create a vector for (this will give you your distance and direction).
* Using the Editor's sketch tool click on the point (it should snap) and that will be your first vertex. Then use CTRL-A, which is an Editor shortcut key to enter the direction. Then use CTRL-L to enter the length. Then Click to set the vertex location. Click F2 to finish the feature.

Repeat for each of your points -- it should take about 20-30 minutes in all. If you're a really experience ArcGIS Python programer, you might be able to write a script to do the same in about the same amount of time. Once you have the first year's data in you can set the snapping environment to also include the endpoints of your vectors to add subsequent year's segments.

You will need the spatial analyst extension to do the velocity contour map.

Mapping Center Answer:

You would use one of the Interpolation tools in Spatial Analyst.  Follow the link provided here to see which one would work best for you.  You can also post this question to the Geoprocessing team a they are the ones who developed the interpolation tools.

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