Wednesday, May 25, 2011

Using to Build a Custom Map for the Flood Fight

Like many areas around the United States, Bismarck and Mandan in North Dakota are dealing with flood-related issues. As usual, there are a large number of maps to help one determine the impact of the water on one's property. Another GIS resource is the North Dakota GIS Hub. We'll go through a very simple example of using Esri's to bring up a basemap and overlay that with high-resolution Bismarck-Mandan contour data. A nice thing about using is that this tool should work on most platforms that don't otherwise play nice with technologies like Flash and Silverlight. So buckle in, here we go.

Begin by going to then clicking on the Make a Map link near the center of the screen. If you get through that step you should be good to get through the rest of this. :-)

You should now see a nice map of the United States. Don't get side-tracked by exploring other parts of the country with this map. We have to get some work done. In the upper right corner, type in Bismarck, ND then click the magnifying glass or press enter. You should now be zoomed in to Bismarck. This is a nice map but it doesn't yet have enough detail to allow us to zoom in sufficiently. Therefore, click on the Basemap button in the upper left and click on the "Streets" base map:

So far we have only been using the Esri data. Now let's add some GIS Hub data, continuing to focus on using data from the Bismarck-Mandan area. By the way, this Bismarck-Mandan data that we'll be using is from 2009 and is courtesy of a joint-funded effort between the Cities of Bismarck and Mandan, the Bismarck MPO, the State of North Dakota, and the U.S. Geological Survey. The imagery and the elevation are both high-resolution.

In the upper left corner, click on the Add button then click on Add Layers from the drop-down. In the "Find:" field enter "North Dakota" without the quotes then click the Go button across from the "Find:" field. You should now see a list of items to select from:

Please pay close attention to the following steps as it is easy to click on the wrong link, arrow, or other doo-hinky.

Click the Add link that is associated with the All_Elevation item. Your screen will eventually go gray, showing some topography.

Click the Add link that is associated with the Basemap_Imagery item. You will now see some imagery appear, hiding the topography.

Click the Done Adding Layers button near the bottom of the screen.

For the moment, remove the check mark in front of the "Basemap_Imagery" item in the table of contents on the left.

Let's work on getting some contours to show up. Click on the "All_Elevation" item in the table of contents then click on the "Statewide" item. You should now see a number of items show up including the one named "Shaded Relief NED 30meter". Remove the check mark in front of this and now you should be back to the streets of Bismarck-Mandan. See this stuff is easy.

Click on the Cities item and then put a check mark in front of the "Bismarck-Mandan 2009 10-foot Contours" item (10-foot means 10-foot changes in elevation):

At this point, you may or may not see the contours show up. If you don't then zoom in a bit more and/or pan to your area of interest. If you don't see contour labels right away, don't panic. Zoom in a bit more and you will see them.

After you see the labels show up on the 10-foot contours, you can now consider removing the check mark in front of that layer and replacing them with the "Bismarck-Mandan 2009 2-foot Contours" which have a lot more detail. Once again, zoom in more to see the labels.

So far you've been using the "Streets" base map. Let's switch to using the high-resolution Bismarck-Mandan imagery. Afterall, let's make good use of our tax dollars! In the table of contents, hover your mouse over the "Basemap_Imagery" item to see a little arrow show up to the right. Click on the arrow and select the "Move Down" item from the list to place the imagery below the elevation data.

Now put a check mark in front of the "Basemap_Imagery" item to turn on the imagery. That's nice eh?!

That's about it. Please remember that these contours (and other data) are always models using the best available data, resources and technologies. Any item on a map will have a certain amount of error built into it, so use ANY map with caution. All data on maps have associated scales, horizontal accuracies, vertical accuracies, and other attributes that together introduce a certain amount of error.

Tuesday, May 24, 2011

Call for Papers - North Dakota GIS Users Conference!

It doesn’t seem that long ago that we wrapped up the 2009 North Dakota GIS Users Conference, and now the conference committee is making plans for the 2011 Conference to be held once again at the Alerus Center in Grand Forks, October 11-13. After having had the conference in Bismarck for years and then moving the 2009 Conference to Grand Forks, we were very pleased with the record number of attendees, exhibitors, presenters, and generosity of the sponsors. More information on the past conference can be found here.

We realize that there are many (too many?) GIS conference opportunities these days and whether you are an attendee, presenter, exhibitor, sponsor, or some combination of all, these conferences consume your valuable time and resources. We invite you to consider providing a presentation, exhibit, sponsorship, workshop, poster, or some combination of all. More information on the conference can be found on conference web site. We sincerely hope that you will be able to join us in Grand Forks!

Friday, May 13, 2011

Using the GIS Hub Cached Base Map Services in ArcMap

There are currently two base maps available from the GIS Hub REST interface, "Basemap_General" and "Basemap_Imagery". Basemap_General displays transportation, boundaries, hydrography, locations, and other data. It also contains a shaded elevation surface for a subtle background. Basemap_Imagery displays the statewide National Agriculture Imagery Program (NAIP) aerial photography and where available, local higher-resolution aerial photography.

These base map services are cached, meaning that literally millions of images have been pre-built at defined scales. Instead of the system having to dynamically generate the entire image on the fly, these many image files are used to build the one image one sees within a web application or within ArcMap. This is the secret sauce for making the map image display very quick during zooms and pans.

You can try out the base map services in ArcMap by doing the following:

  • Click the Add Data button
  • Navigate up in the Add Data window until you see GIS Servers in the list
  • Open the GIS Servers item by double-clicking on it
  • If you don’t already have a connection set up to the ND GIS Hub web services then
  1. Open the Add ArcGIS Server item by double-clicking on it
  2. Select the ‘Use GIS Services’ option, click Next
  3. In the Server URL field, enter and then click Finish
  • Double click the ‘arcgis on’ item
  • Click on either the Basemap_General or Basemap_Imagery item then click Add
  • If you wish to add the other base map, simply double-click again on the ‘arcgis on’ item and then click on the base map you wish to use
  • Maximum image clarity and performance will be obtained if you first zoom in to the desired scale, then in the TOC right-click on the base map name and select ‘Zoom to Nearest Cache Resolution’
  • You may wish to visit the GIS Hub web services page for additional information

Thursday, May 5, 2011

Those Changing Layer IDs

If you use the GIS Hub's Web Map Services (WMS) and/or Web Coverage Services (WCS) you may be wondering what's up with the layer IDs in the WMS and WCS services changing from time to time. If you have an application that references one of those layer IDs and if you don't change the layer ID when notified via the NDGIS listserv or the NDGIS Twitter feed, you may find that the layer is not what you expected.

For example, layer ID 25 currently references the Bismarck-Mandan 2009 imagery. In the future, the GIS Hub configuration may be changed so that the Bismarck-Mandan 2009 imagery uses layer ID 24 and the Bismarck-Mandan 2005 imagery uses ID 25. If you don't make the corresponding change in your application, you will be viewing the Bismarck-Mandan 2005 imagery. So why does this happen?  This didn't happen in the past did it?

As Esri moved from the older ArcIMS technology to the newer ArcGIS Server technology, a number of good features failed to make the transition.  The static layer ID was one of them. In ArcIMS the layer IDs were set by the GIS Hub administrator and would remain named as specified, even if other layers were added or deleted.  This is not the case in ArcGIS Server.  The software sequentially assigns the layers their unique IDs but they are dynamic.  Any layers addedd or deleted will reset the layer IDs.  Hopefully this "feature" will be fixed in a future release of ArcGIS Server.