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TOPIC: Satelite image on HDS screen

Satelite image on HDS screen 7 years 10 months ago #1492

  • gpiverson
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Also, I know this isn't your purpose but I have a responsibility to point out that most of this imagery is licensed and copyrighted and for that reason can't be sold. The OSM maps can with the appropriate license rights (CC By SA) in an attached file.

www.openstreetmap.org/copyright
Last Edit: 7 years 10 months ago by gpiverson.
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Satelite image on HDS screen 7 years 10 months ago #1494

  • Talon
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Thanks Greg...that process worked perfectly. I outlined a map area in SAS Planet, checked Relative Path to Tiles, then Zoom Levels 18-22 and exported the .kml file. Next I brought the "Z18 to Z22" folders from the cache\sat\ folder directly into IMC Raster mode and set the Resolution at 1 and 8 per Matt's recommendation. The Build function worked perfectly and I ended up with a great aerial raster map on the HDS. Some screenshots are attached.

My next step will be to figure out how to get the most zoomed-in level from Google Earth to appear. I have quickly gone from frustrated to picky. The highest level screenshot is not quite as good as the highest zoom image of the same area show from Google Earth.

I can't thank everyone who helped out enough. The ability to accomplish this task is HUGE across many of the Midwest waters!
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Satelite image on HDS screen 7 years 10 months ago #1495

  • gpiverson
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This should help you start to align images to MM/pixel ranges now...

Opening up the jgw files into a text editor will tell you what resolution the images were taken at. Here is one from my z14 directory:
0.00017166137695312 (X Resolution Per X Pixel)
0.00000000000000000 (Y Resolution Per X Pixel)
0.00000000000000000 (X Resolution Per Y Pixel)
-0.00012333332992148 (Y Resolution Per Y Pixel)
-88.72550010681152344 (X Position of Left Most Pixel)
44.08752336158023866 (Y Position of Top Most Pixel)

This is called a Geographic WGS84 projection. Your ranges are from -180 to 180 for X and -90 to 90 on Y.

The Earth is 24,901.55 miles/131,480,184 feet/40,075,160 meters around at the equator. (rough estimates)
The Earth is 69.17 miles/365,223 feet/111,320 meters around per degree at the equator. (rough estimates)

We can say that pixels on z14 tiles are created to be around 111,320 * 0.00017166137695312 (19.1) meters wide and 111,320 * 0.00012333332992148 (13.7) meters tall which means that z14 most accurately corresponds to 16 MM/pixel based on the resolution of the image.
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Satelite image on HDS screen 7 years 10 months ago #1500

  • Talon
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That is great information and it really helps me understand how to calculate the image resolution in a precise manner for future projects. I will rerun this Build with a resolution range from 1 to 16.
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Satelite image on HDS screen 7 years 10 months ago #1502

  • gpiverson
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Each Resolution will require you to run it separately through the IMC with very specific source folders and min/max resolutions.

Here's more specific information:
z5 - 8192 to 8192
z6 - 4096 to 4096
z7 - 2048 to 2048
z8 - 1024 to 1024
z9 - 512 to 512
z10 - 256 to 256
z11 - 128 to 128
z12 - 64 to 64
z13 - 32 to 32
z14 - 16 to 16
z15 - 8 to 8
z16 - 4 to 4
z17 - 2 to 2
z18 - 1 to 1
z19 - .5 to .5
z20 - .25 to .25
z21 - .125 to .125

Everything seems to conform to power of 2 but it doesn't appear the application caches all the high res imagery when required while exporting so a lot of the images are missing...it does a few tiles and then seems to time out or something. The "Don't Store References to Non-Existent Tiles" seems necessary...I get a lot of 4 GB KML files for very small areas so I ran it with the Download Option before Exporting with both options selected and it worked a lot better.

I can see side view mirrors and headlights in z22 so I believe it is 1/16th of a meter resolution.

Note: if you are only exporting from 1 to 16 meter, you'll never be able to distinguish anything above what z18 provides and some of the HDS units are not big fans of sub meter raster...the newer ones all work fine.

Note2: You can run the highest resolution image through but it'll use a lot more RAM while processing and wash out your images when you underzoom it - example: using 1m imagery on 1024 meter output will turn the image gray.
Last Edit: 7 years 10 months ago by gpiverson.
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Satelite image on HDS screen 7 years 10 months ago #1526

  • iron9
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Matt, thank you for your tutorial in post #1474. It worked out just fine.

Regards
Johnny Ahlslied
Last Edit: 7 years 10 months ago by iron9.
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Satelite image on HDS screen 7 years 6 months ago #2692

  • travisgriggs
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The most convenient way I've found to export raster files from SASPlanet:

Within Selection Manager, select the "Stitch" tab.
Select "KMZ for Garmin" as the format.
Select desired map imagery and zoom level.
"start"
SASPlanet spits out a kmz.

Use winrar or any other compression tool to open and unzip the kmz to a file. The file will contain two things. A doc.kml file and a single folder.

Point IMC to the doc.kml, set your desired zoom levels and other options, and you should be good to go.
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Satelite image on HDS screen 7 years 6 months ago #2700

  • gpiverson
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Now that I better understand how the tile system works, storage in KMZ is probably not accurate when zoomed out. The internal resolution for the image caches are Spherical Mercator and KML stores reference positions in Geographic WGS84.

What happens on the imagery is the 4 points are converted and then pixels are linearly interpolated between there. In the West-East direction, this is fine but the Mercator North-South is logarithmic rather than linear meaning your pixels will bunch to the northern side of the tile when processing.

The more accurate way to do this is to store the tiles in their natural Spherical Mercator and then multiply all the coordinates and pixel resolutions by the Spherical Mercator Ratio to get to the Lowrance format - WGS84 SemiMinor (6,356,752.314245) / WGS84 SemiMajor (6,378,137) ~ 0.996647.
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Satelite image on HDS screen 7 years 5 months ago #2846

  • rimart
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I receiving error during creation of raster map with IMC.


My target is to create Sat pictures background for my Reefmaster vector map. Sat pictures I am taking from SAS Planet . Diferent zoom pictures to diferent folders. When trying to create 3DTexture.at5 files for each zoom level . For some zoom levels (9,10,11,12,13) was ok, and I got 3DTexture.at5 for each zoom level. But now for zoom level starting from 14 I receiving this error. What I am doing wrong?
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Satelite image on HDS screen 7 years 5 months ago #2847

  • Hubert
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Just what I have seen in seconds: your source folder and work directory are the same? Use another work directory.
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Satelite image on HDS screen 7 years 5 months ago #2848

  • gpiverson
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It's a random error that was fixed internally but not yet released.

If you run it again, it occasionally goes through.
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Satelite image on HDS screen 7 years 5 months ago #2864

  • LittleGazoo
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Can you use SASPlanet to download Google Earth Satellite Historical Imagery?
How?
Last Edit: 7 years 5 months ago by LittleGazoo.
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