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Author Topic: Experiments with LIDAR  (Read 42120 times)

jbensman

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Re: Experiments with LIDAR
« Reply #45 on: January 05, 2012, 08:24:46 AM »
"Still tweaking this, but here are some examples comparing Mapsource to the Montana. No matter what I do, the Montana just refuses to render as much detail as Mapsource. However, in the sequence below you will notice that as you zoom in on the Montana, the detail seems to actually be there. You just need to zoom in much farther to get it to show."

How many levels and what setings?  If you zoom in and the detail is there, it sounds like a level issue. 

Boyd

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Re: Experiments with LIDAR
« Reply #46 on: January 05, 2012, 10:42:15 AM »
You may be right - thanks, will have a look. The whole concept of zoom levels is something I've just never grasped very well.  :-\

But wouldn't that also affect the way the objects look in Mapsource?
« Last Edit: January 05, 2012, 11:12:46 AM by Boyd »

jbensman

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Re: Experiments with LIDAR
« Reply #47 on: January 05, 2012, 05:25:16 PM »
I've never really understood them either.  I just experminted a lot and found the settings that worked the best.

Maybe you do like I do, set my gps to normal detail and MapSource to most.  If MapSource is set to med detail, the different layers kick in at the same zoom as the GPS.  But when mapsource is set to highest, it shows the greatest detail at amuch higher levels.

I think there are some limits if you set it to 24 bits on how far you can get it to display.  For My Trails, I set zoom 0 to 23 bits as I had too many problms with zoom if I set it to 24 bits.  So I would suggest trying zoom 0 23 bits. 

Boyd

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Re: Experiments with LIDAR
« Reply #48 on: January 05, 2012, 11:39:42 PM »
I've never really understood them either.  I just experminted a lot and found the settings that worked the best.

Haha, here I assumed you were the master of zoom levels, based on all the things you've posted in the past! You certainly seem to have a better understanding than I do.

Nevertheless, after lots of study I'm not sure that's the issue. Seems more like different rendering engines on different platforms. But I've made some major progress today, at the expense of considerable time. It really is all about the palette. Between this and simple use of the gaussian blur filter in Photoshop, I'm getting results I like a lot more. It looks more like a map.  :) I apply the blur filter in RGB colorspace, then convert to my 16 color indexed palette. The result is banding, which creates nice smooth, curvy shapes.

Polygon count is greatly reduced... but the polygons have gotten bigger and more complex, so it's a bit of a trade off. But these look more like the kind of shapes that a GPS is intended to render. Mapsource still shows a bit more detail, but I'm starting to get convergence between PC and GPS.




And it looks much more attractive when you zoom in.


babj615

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Re: Experiments with LIDAR
« Reply #49 on: January 06, 2012, 12:26:24 AM »
Wow, Boyd, the MapSource vs Montana images are almost indiscernible!

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Boyd

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Re: Experiments with LIDAR
« Reply #50 on: January 08, 2012, 11:15:22 AM »
I can't even remember how many times I've thrown everything away and started over from scratch again on this project! But it's finally paying off and I'm getting results that work well on the Montana as well as Mapsource. I have sure learned a lot along the way, all of which makes me more interested than before in converting raster imagery to Garmin's vector format.

Will want to work on this for a little while longer, but will upload the finished map here before too long. BTW, I just started using TypWiz 2 Beta yesterday with my custom types file. It has a few little quirks, but overall a terrific program - get it here: http://pinns.co.uk/osm/ostyp.html

This new version has its own .typ compiler. This addresses my issues with the old version that used cgpsmapper to compile the .typ files. Cgpsmapper does not support all of the advanced styles, such as text sizes and colors so that was an issue with my existing files. But the new version seems to handle this very nicely, although I had to manually make some changes that didn't seem to import correctly from the file I created with the online editor.










« Last Edit: January 08, 2012, 11:30:31 AM by Boyd »

Boyd

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Re: Experiments with LIDAR
« Reply #51 on: January 09, 2012, 02:55:48 PM »
I have been gradually expanding my color palette in order to capture more detail in the lowlands (which were mostly just flat green looking before) and have worked back up from to 32 colors). Seemed to be going well until I hit a quad that was especially "bumpy" and I ended up with over 73,000 polygons.

Cgpsmapper seemed to just roll over and go to sleep over this - hadn't completed after an overnight compile. Kind of surprised me since everything else I've done recently has compiled within about 5 minutes, albeit with less polygons. So I've spent today implementing some basic image compression algorithms in Filemaker. After importing the shapefile I can control parameters that discard polygons which meet certain criteria.



This really pays off - just reduced my test 24k quad from 73,000 polygons to 19,000 with almost no loss in quality - see below. Could probably improve further on this, but I think I'm just gonna make this map now. :)












Boyd

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Re: Experiments with LIDAR
« Reply #52 on: January 09, 2012, 08:58:50 PM »
Still searching for the magic formula :)






« Last Edit: January 09, 2012, 09:26:14 PM by Boyd »

Boyd

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Re: Experiments with LIDAR
« Reply #53 on: January 11, 2012, 09:50:17 PM »
Well I have come a long way in the past couple days, but it hasn't been easy. Using every trick I could come up with, I've gotten a lot more detail into the map. I seem to have hit the limits of cgpsmapper and was having trouble getting these to compile at all. After messing around most of the day troubleshooting, I concluded that the polygons are just too complex. I finally solved that by gridding the terrain into tiny pieces, then reassembling it back into a 24k quad. This slices everything into small polygons and cgpsmapper will compile a full quad in about 3 minutes.

At this point, I just need to sit back and be sure that this is the correct level of detail. The map tiles are pretty big - 3 to 4 mb for a 24k quad. But I like the way they look. :)

« Last Edit: January 11, 2012, 10:34:07 PM by Boyd »

leszekp

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Re: Experiments with LIDAR
« Reply #54 on: January 12, 2012, 09:55:31 AM »
Have you tried using mkgmap to compile these maps? As long as you set the memory usable by Java to a high-enough level (use the Java control panel), it seems to do better on files with a large number of polygons than cgpsmapper, and it's faster as well.

Boyd

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Re: Experiments with LIDAR
« Reply #55 on: January 12, 2012, 10:09:11 AM »
Thanks, will have to look at that. I tried Mapwel and it was pretty fast but the .img file didn't have all the polygons in it. I may just stick with my current cgpsmapper kludge until I finish this project though, since the compiles are now very fast and I've never used mkgmap.

I tried slicing each of my quad-sized tiles into 4 small ones and that gets the individual .img files down to 1MB or less. But it didn't seem to perform any faster on the GPS. So I'm going to resample the images with a bit less resolution, and maybe filter out more of the really little objects. My general sense is that a 24k quad-sized .img tile shouldn't be more than ~2.0 to 2.5MB for acceptable performance on the GPS. Too bad, because Mapsource can handle 5 or 6MB .img tiles with no problem.
« Last Edit: January 12, 2012, 10:14:17 AM by Boyd »

Seldom

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Re: Experiments with LIDAR
« Reply #56 on: January 12, 2012, 11:19:26 AM »
Have you tried using mkgmap to compile these maps? As long as you set the memory usable by Java to a high-enough level (use the Java control panel), it seems to do better on files with a large number of polygons than cgpsmapper, and it's faster as well.

What version of mkgmap are you using, and are you using it on MP files or OSM?  I follow the mkgmap mailing list, and it still sounds like a work in progress.  Are you generating routable maps, and if so, is address search working reliably for you?

The last time I tried it on MP files I got some funky edges between adjacent tiles.  Since then, I just use it to compile OSM data that I convert to MP and compile w/ cgpsmapper.

leszekp

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Re: Experiments with LIDAR
« Reply #57 on: January 14, 2012, 10:25:34 AM »
I'm not doing routable maps, just maps with custom TYP files (including subtypes) and lots of polygons. I've been using release 1995, though I may try the most recent release series (21xx) in the near future.

Boyd

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Re: Experiments with LIDAR
« Reply #58 on: January 14, 2012, 12:33:38 PM »
My kludge is working well now, so I'm just sticking with it. I uset the export > grid option to create a lot of little tiles, then re-import and combine into a single layer. These compile really fast in cgpsmapper, typically less than a minute. The longest was about 7 minutes.

I have 24 out of 55 quads finished and the .img files are mostly 1mb - 2mb, with the largest being 2.4mb. These seem to perform well on my Montana, even in the car but will do some more serious testing soon.


Boyd

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Re: Experiments with LIDAR
« Reply #59 on: January 15, 2012, 11:36:16 AM »
Did a brief road test today, and it works very well, even on the lowly Nuvi 205. Also works on the 60csx, but screen updates are rather slow.




3d mode on the 3790 looks pretty cool. Would love to see how it looks on the new 3550 which has a 5" glass multi-touch screen. :) https://buy.garmin.com/shop/shop.do?cID=401&pID=74086

« Last Edit: January 15, 2012, 12:31:03 PM by Boyd »