Hey Dummy...Quit ignoring GIS Servers in ArcCatalog

Ok. So I am not so smart...big surprise. It is digital geoscience for dummies after all, and I am a geologist, not a GIS-geek. At the DMT meeting last week I was able to have several head-to-heads with some well-trained ESRI representatives. I learned more than I can remember now, but the key thing I learned is the value of the network connection/ gis server function in ArcCatalog. Yes, I have always seen it and always ignored it. Whoops. With recent developments at ArcGIS online, you can link your mxd to various streaming sources of data. If you use ArcGIS, you need to check out ArcGIS online.

I started to get a whiff of this when using Topofusion (see previous posts) and, more recently, Global Mapper, because these programs can load imagery in the background of your project when you are online. Anyway, check this out:


The image above shows my Ivanpah Valley, NV megamap (the flood hazard version) at 1:250k with high resolution ortho imagery in the background. Also, check this out:


ESRI provides a decent data set of shaded relief for the globe. This is what southern Nevada looks like. The shaded relief looks considerably better when zoomed out over a larger region and makes a great overview map.

You can also 'be served' some pretty decent satellite imagery, as shown below:


So, how does this work? Pretty freaking simple. Create Network Connections in ArcCatalog. You just need to decide if it is an ArcGIS server, an ArcIMS server, or an WMS server. Then you simple add the server data source to your active project much as you would imagery or data hosted on your desktop computer. Of potentially great interest is the fact that you can connect to seamless.usgs.gov and choose the data type that you want to add from a long list.


Note: The high resolution imagery available at ArcGIS online is the new color NAIP orthoimagery (I'm pretty sure), so it is completely viable as a geologic mapping supplement. I wish I had known about this long ago. Being self-taught in GIS has its disadvantages. If any of the 4 people out there who may look at this blog know of any other online map services of value to geologists, let me know.

Mandatory (Basic) Image Enhancements

Smooth Your Image:


To get the most most out of your base imagery, you need to experiment with different image enhancement tools in Arc. The basic manipulations can be found under the 'display' and 'symbology' tabs found under 'layer--properties' (right-click on the layer of interest). To smooth the image without any negative effects, choose the 'bilinear interpolation' option and then click 'apply'. This will smooth your image in a visually satisfying way. Other resampling options may result in bothersome artifacts in the typical types of imagery that geologists use for mapping.

Stretch Your Imagery:

Stretching your image can create levels of contrast and color balance that you will appreciate. For details, consult a remote sensing textbook. For now, just accept the fact that you can vastly improve an image's appearance by applying a standard deviation stretch to your data. Start with n=2 and experiment with increasing and decreasing this value. Also, if you limit the stretch statistics to the 'Current Display Exent' you will get ~local results that typically improve the contrast of the image. This will vary with the absolute range of values present in the current display. Experiment with other stretches.

Both of these enhancements are useful for b/w DOQQs, color DOQQS, and Quickbird data among (presumably) all other remotely sensed base (photo-like) imagery. It is not useful for DRGs.