2011/11/26 Michael Barton <michael.bar...@asu.edu>: > While I understand the problems, if we revert it, it will be much worse. The > initial z-exag will be set to 1000 for latlon and even a value of 1 will be > enormously too big. This is why I tried to improve it. > > The previous way it was working was even more arbitrary than it is now. It is > making no conversion whatsoever between degrees and meters. It is simply > using a ratio between the maximum vertical range and the maximum horizontal > range. So the conversion factor is much different for areas of high mountains > than for areas of low hills. And then the conversion factor was arbitrarily > rescaled by a factor of 1, 100, or 1000--only one of those 3 values--to reset > the decimal point. > > Moreover, what does a vertical exaggeration of 0.0001 mean? To most people, I > think that means that the vertical exaggeration is much much less than the > "real" value, not a 1:1 vertical:horizontal ratio. > > We need to fix this properly. Reverting it will only make it even less useful > than it is now. > > Once I make a bit of time in the next couple weeks, I can dig back through it > to find the places in the code where this is set (one is exag.c). Then maybe > you all can take a look at it to see how best to improve it so that it works > right. Does that sound OK? >
I don't use nviz for real work so I can't say which behaviour is more user-friendy, this is just my point of view. I hope we can find some better solution. Anna > Michael > ____________________ > C. Michael Barton > Director, Center for Social Dynamics & Complexity > Professor of Anthropology, School of Human Evolution & Social Change > Arizona State University > > voice: 480-965-6262 (SHESC), 480-727-9746 (CSDC) > fax: 480-965-7671 (SHESC), 480-727-0709 (CSDC) > www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu > > > > > > > > > > > > On Nov 26, 2011, at 12:49 PM, Anna Kratochvílová wrote: > >> 2011/11/26 Hamish <hamis...@yahoo.com>: >>> Helena wrote: >>>> - in wxnviz to avoid the very small zexag for latlong, >>> >>> another idea for lat/lon z-exag: just figure out what is 20-25% of the >>> canvas height (or ~15% of the north-south image width), >>> and work backwards from there, rounding to the nearest nice >>> round number. >>> >>> I don't know if there is any real way to escape from x:y:z ratios >>> of 1 : 1 : 1/(1852*60), as anything other than that is numerically >>> synthetic. if taking up the 1:cos(lat) aspect ratio adjustment >>> perhaps rather than converting the elevation data to degrees, >>> we could convert the ew, ns to "meters" to get ratios of >>> 1852*60*cos(lat): 1852*60 : 1 as the cheap and dirty projection. >>> for global lat/lon views you probably wouldn't want to do that >>> though. >>> >>> >>> Hamish >>> >> >> Hi, >> >> I think we should revert the changes in zexag, it's the only way to >> set real exaggeration. Very small zexag values with lat/lon maps are >> inconvenient but still it works. I like the possible solution with >> 1852*60*cos(lat) but I'm not sure I'll be able to implement it, I >> remember I tried to do something similar but I couldn't get it work >> (OGSF is quite messy). I can try again (but not now, maybe in the next >> few weeks). >> >> Anna > > _______________________________________________ grass-dev mailing list grass-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-dev
