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TOPIC: Processing Islands of Hi-Res Imagery

Processing Islands of Hi-Res Imagery 1 month 1 week ago #12264

  • SkunkApe
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I have a survey block with an area of extent of about 50 square miles. The source multibeam sonar imagery for this survey has 1 meter resolution, with the exception of 5 small areas within the area of extent that contain notable features (referred to as "footprints" in this case). These footprints where mapped at 50cm resolution. In the surveys performed off our coast, It's common to have a survey block with most of the area mapped to 1m and the footprints with features mapped to 50cm. When creating shaded relief maps in ReefMaster using these sonar files, I used to export the Map Project with IMC set to Max Resolution = 512 & Min Resolution = .0625 (to match to highest resolution of the source imagery I'm working with). That works fine and results in some real crisp imagery on my devices, while the at5 file set usually comes in under 64GB (considering I use reformatted 64GB cards). I have had some projects that went over 64GB and that causes all kind of problems having to start over with the Map Project export process and how all the pieces of the imagery mosaic fit together once completed.

To mitigate Map Project exports going over 64GB, I'm exporting the Map Project for each resolution level instead of letting IMC run through all the resolution levels until it's finished. That way I can process the all the 1m & 50cm source imagery down to .0125 resolution, then turn off all the 1m files in the RM layers panel and change the footprint's "clamp to polygon map layer" from the larger area of extent polygon to individual polygons surrounding each small foot print area. I'm required to run the Generate Map process because my map boundaries have changed. when After I run the Generate Map process (between levels .0125 and .0625) Islands & Shoreline layers now appear my layers panel. This is where I get confused because, yes, the footprints are technically island, but when I export the Map Project to process the footprints at .0625 imagery, RM never stops generating .png & .kml files into the Temp -> source folder and IMC never picks up the files or initiates the .0625 at5 file generation phase. I thought running Generate Map in between Map Project exports might has disengaged the IMC utility, So I tested with just one footprint, and it works fine. I have my entire area of extent processed down to .0125 and one little mini-map that's processed to .0625.

Is RM designed to do what I trying to do? Let me know if you have any questions, I'm sure I made it a bit confusing trying to explain all that.

Last Edit: 1 month 1 week ago by SkunkApe.
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Processing Islands of Hi-Res Imagery 1 month 1 week ago #12266

  • Matt
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I think I understand what you are trying to do, but just to clarify - when you export at the highest (most zoomed in) level of zoom, are you only exporting the images within the circles?

A few observations:

It looks like you have a set of images, and are simply exporting them either together or with different polygon clips. You shouldn't need to regenerate the map when you change the polygon clipping for the image(s), so I'm not sure what is going on here. Do you have shorelines/islands set up? Are you generating vector layers as well as using the images in your map?

Clipping an image will/should limit the area that RM needs to generate for the IMC raster process, but it will still generate an area defined by the bounds of all visible clips. In your case, that looks similar to the size of the total image, so there is not going to be much saving within RM or the IMC here. The extra time taken by RM to generate the IMC input files might just be because of the zoom level selected. What you could try is exporting each clipped zone independently as a set of raster image files, collating all of these into a single folder and then running the IMC manually. This will save a lot of time within RM.

If I've misunderstood, let me know.
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Processing Islands of Hi-Res Imagery 2 weeks 1 day ago #12280

  • SkunkApe
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Sorry for the delay on getting back to your questions, and thanks for your informative response.

So my goal was to do this:
Preface - I I have six polygons created before I start the map project exports; one big one that defines the 50 square miles of 1m & 50cm area of extent, and five small circular polygons that define only the areas of higher resolution 50cm imagery. Only the big polygon is checked and visible at the time I start the exports, the 5 small ones are unchecked and not visable in the RM map dispaly (yet).
1. Define the large area of extent containing the 1m & 50cm imagery with the big polygon (as seen in image #1 above).
2. Then export each resolution level (from 512 down to .125, one level at a time) making sure the Project Base Naming and Atlas Description remain the same throught the map project exporting process.
3. After level .125 completes exporting, I uncheck the big polygon bounding all the 1m & 50cm imagery, then activate the five small circular polygons that bound only the 50cm resolution imagery (as seen in image #2 above). So all the 1m imagery is clipped out, and (in theory) RM exports only those five small areas of 50cm imagery to be processed by IMC at resolution level .0625 WHILE still retaining the same Project based naming & Atlas Description that I exported all the other resolution levels under.
4. The resulting compilation of .at5 files would load as one chart on a plotter (since all files have the common Project base naming and Atlas Description; and from a users perspective, all imagery would display seamlessly until the chart is zoomed down to the highest resolution threshold that supports 1m imagery, whereas the all 1m imagery would disappear and only the five clipped areas of 50cm imagery would display. So I still get to see my 1m and 50cm imagery as one chart without the 60gb of unnecessary data on my(reformatted 64gb sd card), and I don't have to go to my Chart Sources to select separate 'mini-map' which I would have had to create to accommodate only the 50cm imagery at resolution level .0625.

So long confusing story made short:
1. Export all imagery areas defined by one large polygon (roughly 50 squares miles) for levels 512 down to .125, then....
2. Deactivate large polygon, then activate the five small polygons which contain only 50cm imagery and clipping out all 1m imagery, then export only 50cm imagery at level .0625.

But I think what you're saying is that RM can't selectively process only those five polygons (islands?) of 50cm imagery when running the final export at resolution level .0625., It will also process all the no data which surrounds the 50cm imagery as well, which subsequently exports a huge data set of useless .at5 files at resolution level .0625?

I'm still a little confused, because I thought if I have islands defined by polygons, RM would ignore everything except the islands areas when doing a map project export? I guess I need to read up on the RM Help topics again to try to understand how island, land and shoreline settings work so all the surrounding nodata is ignored and only my areas of interest are exported.

Not a typical Reefmaster Use Case scenario, I know. I wouldn't be at all surprised if you just posted a 'roll eyes" emoticon as a reply to this post, locked the thread and moved on. haha. J/K, and again I really do appreciate all the hard work and support you've provided over the years.


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