OziExplorer problem

thanks Steve, but Andrews suggestion (below) to create a new mapfile for the downloaded map worked just fine

I've found the easiest way since using the PDA instead of the laptop is to open the map in Ozi on the PC, make sure it is working ok (map files etc are correct).
Then convert it to ozf3 and save it into a seperate file for each trip. This way you can download the required maps for each trip onto the mem card when required.
Then download it into the card in the pda using a direct cable rather than the docking station as the dock 'freezes' occasionally during large file transfers.

the version i'm using can (& does) use the ecw files so no need to convert

Hello - I have found ecw files to be a bit slow loading/updating on the PDA (though it does depend on file size). I would recommend converting to OZF whenever you can. The resulting OZF file may or may not be larger in size than the ECW - depends on the compression ratio used to create the ECW file. From my expereince you will not normally see (because there is none?) any loss in image quality when converting your average map to OZF - unless you dramatically change number of colors to get a smaller file.
Cheers
Greg

Thanks Greg.....Just tested the conversion of this ECW file to Ozf2 or Ozf3 format , would be about 8.12mb and 7.51mb respectively using 256 colours. Would be interested to see the balance between these larger file sizes and the speed of loading/displaying with this map (i'm aware of how the formats load WRT oziCE etc)

Andrew

Andrew - I was speaking in general terms and based on my use of some pretty big ecw files (airphotos), maybe not applicable in this case - I rarely use the 250K maps on my PDA (in any format - not enough detail) and so can not state specifically in this case whether ECW is better or worse than OZF (with respect to loading and panning). I have a lot of 25 and 50k maps as OZF3. They are converted from about 80mb tiffs to about 10mb OZF3. I have also converted some to ECW (compression set at 10) - file size is smaller ..say 60% of OZF. The OZF load on my PDA (ipaq 2790) in less than a second...the ECWs slightly slower ..maybe 1 second. When panning the OZF appear to load a fraction faster also. So it appears for smaller files (up to say 20mb) there is didley squat difference between OZF and ECW - there is a difference but it is not what I would call significiant or likely to cause frustration in the bush (not good)...so as you suggest ecw in this case (250K maps) would be the go if you're tight on memory. But over all I like OZF3 better..SD cards are pretty cheap.
Cheers
Greg

thanks Andrew .. your answer was spot on & the mapfile created by OziExplorer works perfectly

That's ok, Greg......It's good to know that info. Personally i like to keep my maps as high resolution as possible. I normally use aerial photographs in TIF format (LZW compression), around 17-270mb :-) I have found that when using aerials, it pays to keep the colours in the resulting image, and therefore any conversion to 256 colours or less (eg ozf2/3 etc) results in less than ideal images (especially when containing water etc) for my purposes. Thanks for the better understanding of the differences when used on a PDA.

I suspect that the conversion/compression used by GA to make the ECW files are of such a nature that they are the best balance of compression and colour factors.

Drew T, i'm glad that the information helped.....

Andrew

Just for the record - not all PDA's that can use OziCe can open ECW files - something to do with processors - only units with ARM processors can utilise ECW images...others are restricted to OZF format.

Cheers
Greg

Leigh
No need to convert ecw to ozf3 to use on PDA...