Re: [Viking-devel] Calculating UTM coordinate from screen position

2020-04-09 Thread Greg Troxel
Robert Norris writes: > The projection is done based on the zone at the center position. > > The zone is for the east<->west, whereas the designation letter is the > latitude band, being 8 degrees wide, which Viking currently shows as part of > the UTM readout. > > This use of the from screen p

Re: [Viking-devel] Calculating UTM coordinate from screen position

2020-04-09 Thread Robert Norris
> If the screen projection really is UTM, then it is in some zone as > determined somehow, arguably best by the proper zone for the central > point. This lets you convert lat/lon to UTM even if you end up in the > wrong zone. Most conversion code lets you force the zone, as opposed to > finding o

Re: [Viking-devel] Calculating UTM coordinate from screen position

2020-04-08 Thread Greg Troxel
Robert Norris writes: > I don't think Viking is used much in UTM as a general purpose viewer - > since there aren't many if any tile sources in UTM projections. More > typical is probably using a GeoRef layer to view an existing map image > (this is the way I use it in order to test it's working)

Re: [Viking-devel] Calculating UTM coordinate from screen position

2020-04-08 Thread Robert Norris
>I would like to ask a question regarding calculation of UTM letter in >vikviewport.c/vik_viewport_screen_to_coord() >function. >However the code doesn't seem to consider a case where the input screen >position may be located in another >latitude band. The band letter in >resulting utm variable

[Viking-devel] Calculating UTM coordinate from screen position

2020-04-06 Thread Kamil Ignacak
Hello, I would like to ask a question regarding calculation of UTM letter in vikviewport.c/vik_viewport_screen_to_coord() function. The following code is recognizing a possibility that input screen position passed as function's argument may be located in neighbouring UTM zone, therefore a zone_de