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Old 08-10-2018, 04:24 PM
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PlayDoh PlayDoh is offline
Join Date: May 2008
Location: Strathmore/Calgary
Posts: 953
Lightbulb my trick to mark spots using bathymetric and google maps

So I've developed a way to mark a spot on google earth, using the bathymetric maps, overlayed onto google earth. I then mark spots of interest, and then save them on google maps, so when I'm out on the water I can use my phone to GPS me to them.
Kind of a poor mans Navionics, or lakemaster if you will. It works great, yet with a sonar it can much better understand what the bottom looks like under you. I have a GPS HB sonar, so I mark spots on it once the phone gets me there, so I don't need both after trip 1.

Its a little convoluted, and I'm not sure why Google hasn't made this task much easier, by simply letting you save spots to google maps with an option on Google earth. I've looked to see if theres a way, but no dice. If anyone knows of a way, I'd appreciate the tip.

So, heres a run down of what I do. I'll post pictures of screen shots below with details.
I download the Bathymetric maps from the government site. Their PDF, so you either screen shot the PDF on screen to get an image to work with, since the PDF is password edit protected. Or use a program or online service to unlock the PDF, and convert it to an image.
Now I use Photoshop to edit and manipulate the images, but there are other options. You don't need to do much, just some cropping really. I do the lake in 2-4 sections as its easier to line up with google earth. So once I have my half or less of a lake image, I go to GE (Google earth), and go to the desired location.
Next you select "add image overlay" from the top "add" menu item at the top. select the image you've made from the Bathymetric map.From there you'll need to use the 6 green points to enlarge or shrink the image. Also the diamond on the left of the image will rotate.
This part takes some time. Make sure the google earth is set to a straight down view (click and hold mouse wheel). I recommend using roads and other landmarks to help. slide the opacity or transparency slider so see both landmarks at the same time. I zoom in on the corners, and it never "perfectly" lines up 100%. thats why the smaller the picture you start with the more accurate you will be at lining up. You can and should overlap the images, to help you line up things.I didn't screen shot that process, but if you can get one to work, thats not a problem.
Once your done aligning the overlay, set the transparency to max and name it and click ok. Now you can scout for steep drop offs and sunken humps. Mark them with the GE 'add placemark' (thumbtack icon). I'll often use a few to give me the 4 corners of a hump, or a line following a contour, etc.
when you have the place-mark properties up, copy the GPS coordinates, and paste them into your browser or Google map app. Since your on a PC a browser window is much easier. You have to copy and paste the coordinates half / one at a time (Long & Lat). hit search on Google maps once the coordinates are both in, and then select "save". I save them to "Starred" places, but do as you like. You can also select "send to your phone, or email, or someone elses number.
Now you have the location available on your phone, and as long as you have data, your poor mans lakemaster is ready to go.

I'll start a reply with the images of screen shots.
Theres a fine line between fishing and just standing on the shore like an idiot.
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