Tuesday, January 19, 2010

Custom GPS Enabled Fishing Maps

I've spent the last couple of days moving all my map and depth data over from my old laptop to my new netbook. I also sat down and finally worked out a way to make layered maps from GeoTIFF's and retain the EXIF geodata so they can be autocalibrated in my mapping programs. The first set of maps are hydrographic maps made by the US Army Corps of Engineers. You can find them here. The particular map I'm going to be using can be found here.

These maps aren't GPS calibrated and come in two forms, Adobe PDF and Autocad DWF files. You can download free DWF viewers from Autocad. This particular map is a PDF and what I do is blow it up to the size I want and copy the section of the map I want using the 'Snapshot' tool in the 'Tool' menu. Then I paste it into a graphics/photo editing program like Irfanview or The Gimp (Both are free) and then save as a PNG, TIFF, or JPG file. Most mapping programs seem to work best with PNG or TIFF. Next I bring it into my mapping program for hand calibration. Since these maps have a grid in UTM format I have to convert from UTM to lat/long decimal degrees. For this I use another freely available program from the USACE called CorpsCon. Once I convert all the UTM grid lines to lat/long I then calibrate the map in OziExplorer using a minimum of 3 points and usually use as many as possible to make the map more accurate. Now my map is ready to use. Here are some screenshots of my map with Waypoints added.

This is just a general overview of the area I'll be showing. Please note that the depths shown are at Flat Pool which is 2.5 ft so you have to get the current water level and adjust. For instance if the tail is at 5.5 feet you add 3 feet to the shown levels

This map is by the Interstate 280 bridge and it shows my most productive spots for fishing. Last July 6th on a full moon I caught 5 Flathead catfish on spot 1 and 3 more on spot 2 for a total weight of a bit over 50 pounds. Fishing the edge of this drop off and the ledge parallel to the shore has also been very productive for channel cats. These waypoints were originally marked a couple of years before I made this map and it was interesting to see how lined up with the dropoff

This final shot is up in the Credit Island Slough (Davenport, Iowa) and shows 3 rock piles that were once footings for barge piers which are below the surface of the water most of the time. This is an excellent spot for catching sunfish and bluegills for flathead bait but hard to locate without the GPS and map

As far as I know I am the only one that is making fishing maps from these hydrographic maps from the USACE but I have found them to be invaluable. In my next post I'll show you another source of maps I use (My main source) and some maps from it that cover these same areas as well as a unique layered photomap like none I've seen elsewhere.

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