GPSFileDepot.com
 

News:

Welcome to GPSFileDepot!

Main Menu

White Tiles Sierra Raster maps

Started by hnaamyilkemku, April 15, 2011, 12:08:27 PM

Previous topic - Next topic

hnaamyilkemku

I just followed gpsfiledepot instructions exactly to install mapsource and download maps to my Garmin Oregon 450. I download the California Sierra Raster files (with an executable), saw them in mapsource, picked the tiles I wanted, then uploaded them to the GPS unit. I see the tiles that I uploaded on the GPS unit in the map mode, but they are white! Even if I zoom in to 200 ft or closer, none the white tiles show any details. The pattern of the white tiles follows the pattern of tiles I picked to upload to the GPS, so I'm sure the right ones are there, but why can't I see anything? Please help, leaving for a marathon Sierra ski traverse very soon.

hnaamyilkemku

OK, I can't get the Sierra raster maps to work, so I tried the california topo maps. I see streams and trails zoomed in, but can't see the topo lines. the file is only 468k or something; I can see the topo lines in map source but NOT on the gps, although I can see trails and water on the gps. Help! I uploaded waypoints successfully and will have a map, so I guess this isn't the end of the world, but it would be nice to have topo lines on the gps...

Boyd

Now that does provide a bit of a clue. There is a bug in the Oregon firmware (unless it's a "feature") related to the profile feature. Depending on setting, it can cause the elevation contours to disappear. Have you edited the original profiles on your Oregon? What profile are you currently using.

If it's not the defualt "recreational" profile (I think that's what it's called), you might have this problem. Regardless of what profile is selected, switch it to something else, then switch it back to recreational and see if that helps either of your problems.

hnaamyilkemku

Thanks for your suggestion, Boyd. I switched to 'fitness', looked at the map, zoomed in all the way, still no topo lines, switched to recreation and did the same thing, but still no topo lines. Any other ideas? =/

Boyd

I think someone else will come along and help, but this map has been discussed before and may have issues. Also, I seem to recall that it's actually two separate maps - one with elevation contours and another with the other features. Both must be loaded and activated together IIRC. But I've never used these myself...

hnaamyilkemku

Got the *other* CA topo maps working... but these are 40ft contour ones and I would prefer the 20 ft contour ones. I will use these these weekend, but if anyone can chime in on getting the CA topo ones to work I would be grateful ;-)

maps4gps

Use the marquee tool to select the quads/segments.  In MapSource, the window on the left will list the quads/segments selected.  There should be some which are numeric and some which are alpha; forget which is which, but one are the contour lines and the other is everything else.

Depending on your area of interest, the 40 foot contours are more in line with the contour lines on the published 24k USGS topo quads.  USGS uses various methods to create an elevation grid from the digitized contours; map authors can use various computer programs (some with default settings which can be changed to various values - some valid, others not) to create contour lines at any interval you choose to use.  In my opinion using an interval of one-half or one-quarter of the interval of the source is like using a copy machine to enlarge a printed topo map, then drawing one or three lines between the original contour lines.  It may look nice, but there is nothing to support exactly where between the known lines those additional lines actually are.  Similiar to printed maps where you know where the land surface is along the contour lines, but only have limitations on where it might be between the lines.  In addition, over contouring can create a blob of lines making it very difficult to see the other information - there have been a few posts on this issue and the CA topo map in these forums.  The data is usually defined at about the 800' display zoom level - zooming in further simply proportanetly seperates the data but does not add and additional detail.  For an older person, the added lines makes it mentally easier to climb mountains (faster progress between lines) even though there are twice as many to cross.

Boyd

Quote from: maps4gps on April 15, 2011, 04:27:45 PMFor an older person, the added lines makes it mentally easier to climb mountains (faster progress between lines) even though there are twice as many to cross.

Maybe it's time for me to double-up on contour lines myself.  ;D

maps4gps

 ::) But the largest elevation changes you have in New Jersey are barely moderate hills. ;)

Boyd

Actually, this is something I've been playing with recently, as there is very good NED19 coverage in Southern New Jersey. This "mountain range" is less than 200 feet high




I have been playing with 1 foot contour intervals.





Based on the test map I've been using on my GPS that uses a 5 foot interval with the NED19 data, I fear all the current garmin models will choke on this much data.  :o

Of course, in the Northwest corner of NJ we have a spectacular place known as the Delaware Water Gap. Hardly the Rocky Mountains, but there are peaks in the 1200 to 1500 foot range. It's about time to make my first trip of the season up there and climb a few of those mountains, just to shame myself into getting back into shape after the long winter.  ;D



maps4gps

I did some test with the 1/9 arc sec LIDAR data of the local area with a 1 ft CI and even 0.5 ft. 
Besides the data size issue, I expect that only being able to define the coordinates in the .img files to 360 degrees / 2 ^ 24 (at max) will not only 'snap' the locations by as much as they might differ and that we may also start seeing points on lines sharing the same 'grid' location because that is the nearest grid location each can 'snap' to.  I would say we now have some data available that in some areas can be used to create contour lines at intervals which can be tighter than the GPSr units are capable of displaying properly.  One must remember that Garmin probably designed the format to match the then available 24k and 20k scale source data. 

Boyd

#11
Hadn't even thought about that, but I'm sure you're right. I started a thread last year about how the MP format didn't have enough resolution to capture the detail in a Globalmapper file of trails on my land. I haven't tried to make an .img file yet with 1 ft intervals - that was a Globalmapper screenshot above.

However, I have used the LIDAR data to create 5 foot contours in my area, and it results in some big files. It's not just the contour interval, but the complexity of the lines due to the "bumpiness" that is captured in the images. I have used the Globalmapper function to simplify lines to help keep the file size down. This a screenshot from an .img file.



(Apologies to hnaamyilkemku for hijacking the thread  :) )

hnaamyilkemku

Thanks for the input, folks! I'll try this when I get home.

The 40 foot contour intervals sufficed for navigating at night during my 2-day Sierra ski traverse, but it would have been fun to have had names of peaks and other features. At one point the digital compass freaked out and the GPS showed an impossible location, but that was just one time out of many.






leszekp

The Sierra raster files were created with my Moagu utility (http://moagu.com) using the original data format, which only works on the Garmin 60C(S)x/76C(S)x series and some eTrex models; they will not work on newer models (Oregon/Colorado/Dakota/62/78 series). Vectorized USGS topo maps using the BMap2MP utility in Moagu will work on these newer models; see http://moagu.com/?page_id=9 for links to some sample maps, and screenshots from my Garmin 62s.