Using satellite pictures for creating accurate lake/reservoir contour map.

Started by smith, January 13, 2009, 09:30:16 AM

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After figuring out how to create a map that works on land, with you guys helping of course ;D thanks.

I'm thinking about building an accurate contour map of the reservoir that I fish.  It would be easier if I could just buy one that actually had good info built in.  After looking at the preview from "Inland US Lake Map" for the lake I fish on Garmin's site, I'm convinced that they directly copied the depth contours that the State published as a PDF file.  Using that map in paper format, I've run aground in an area that was marked at 15' deep on the map.  At least I didn't trash my lower unit.  The deepest part on the map was confirmed on my depth finder and matched what the map said.

The water level of this reservoir has varied around 25' in the last few years.  Looking on google earth the satellite pictures at different zoom levels show the lake at very different depths.  Some of the images during low water show some great structure for fishing when the water is up.

Can I get accurate satellite images from different dates/water levels and just trace the shoreline to produce an extremely accurate contour map?  This would be too easy!

If so, Is satellite imagery "freedom of information" stuff that can be obtained for free If you only know where to look for it? Or, is it only available from terraserver for big $$$$for EACH download?



QuoteWhere is the lake at?
N 44 43.434'
W 103 41.871'

Back in '96 I bought a 17' walleye boat and the first time I went out on this lake, fog rolled in after dark.  It took me hours to find the boat dock with a spotlight.  Not long after I found out how easy it is to navigate in the fog on this same lake in the dark WITH a GPS 12XL.


Thanks for the links.
I've looked at this lake at quite a few different sites and there are different pics available.  I was hoping there would be a cache of info available where one could look at many different images and compare the dates with the water level data that's available.   The water level is monitored 24/7. 

I might have to get some of my info the hard way by driving around the shore on my 4 wheeler and just saving the tracks.  I might try and geotag some photos to show the structure that's hidden when the water level is high.  If you're fishing in a featureless lake the size of a football field and the only structure is one rock the size of a baseball somewhere in the field, you'll find fish next to the rock.  The only problem is finding the rock under 15' of water.  It would be very easy to find that rock and mark it's location when the water level is 25' low and fish that exact location when the water rises.

Another thing I will need to consider is with the water level varying 30' or more because the res is built for irrigation, I may need to create different maps to compensate.  Gotta start somewhere. ;D


It intrigues me how we all use maps for a different purpose.  Everyone wants different data; it is awesome.

30' variation is standard though, thats nuts.

In Arizona we were 30' low; but it never really came back up...
Dan Blomberg
Administrator - GPSFileDepot
GPS Units: Garmin Dakota 20, Garmin GPSMap 60csx, Nuvi 255W, Nuvi 250W, ForeRunner 110, Fenix 2, Tactix Bravo, Foretrex 401
See/Download My Maps!


Here's a link that allows clicking different map sources.  I don't think I can download the pics.
With this I can see at least 3 different water levels.  The only way I can figure out how to convert this to actual contour lines is by moving the cross hair around the shore and recording the lat/lon and drawing this in mapedit or something.  Sounds kind of slow. 
USAPhotoMaps allows one to draw a route over a pic.  This I could get started with. 

If you know of a better program that I could draw over pics with, let me know how to get there ;D



Is the NMEA data stream stored? If it is, is it a format that can be easily converted, like a DEM?


From the look of the gear, I'm assuming that the data is a sort of underwater track log?  So to develop contours for the bottom of the area of interest, I'd have to paddle back and forth on a 50' grid, and then connect the points by hand in a map editing program?