Hi Andy,<br><br>I think it's great that you've fixed the bug. I read your emails with interest but, as it's not my area of expertise, I didn't write back. As far as changes to the GRASS source goes, I do think that the grass-dev list would be the right place to take up such issues. You'd have my blessing at least ;)<br>
<br>Best,<br>Daniel<br><br><div class="gmail_quote">On Sat, Jul 2, 2011 at 8:10 PM, Andy Wickert <span dir="ltr"><<a href="mailto:wickert@colorado.edu">wickert@colorado.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
SOLVED:<div><br></div><div>Built and installed GRASS 6.4.2 from svn, and added a line as noted below; inserted at line 101 in 6.4.2 (see surrounding lines for context). Recompiled r.water.outlet and it works like a charm.</div>
<div><br></div><div>It is totally obvious that this is not an issue that anyone on this list knows/cares about, so could someone at least let me know where to take it such that can get incorporated into the GRASS source and no one else has the same problem? I'm thinking the grass-dev list, but I'd rather not use a loudspeaker to have another conversation with myself if I can avoid it :)</div>
<div><br></div><div><div><span style="white-space:pre-wrap"> </span>G_usage();</div><div><span style="white-space:pre-wrap"> </span>exit(EXIT_FAILURE);</div><div> }</div><div><br></div>
<div> E = G_adjust_east_longitude(E,window.west); // <-- NEW LINE; for using lat/lon data that straddle the 180 meridian</div><div><br></div><div> if (E < window.west || E > window.east || N < window.south ||</div>
<div><span style="white-space:pre-wrap"> </span>N > window.north) {</div></div><div><br></div><div><font color="#888888"><br clear="all"><span style="border-collapse:collapse;font-family:arial, sans-serif;font-size:13px">Andy Wickert</span><div>
<span style="border-collapse:collapse;font-family:arial, sans-serif;font-size:13px">PhD Candidate<br>University of Colorado<br>Geological Sciences & Institute of Arctic and Alpine Research</span><div><span style="border-collapse:collapse;font-family:arial, sans-serif;font-size:13px">1560 30th St.</span></div>
<div><span style="border-collapse:collapse;font-family:arial, sans-serif;font-size:13px">Boulder, CO 80303<br>Office: RL3-275<br></span></div></div></font><div><div></div><div class="h5"><br>
<br><br><div class="gmail_quote">On Sat, Jul 2, 2011 at 3:01 AM, Andy Wickert <span dir="ltr"><<a href="mailto:wickert@colorado.edu" target="_blank">wickert@colorado.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>So, in short, I think that we could add the following at line 106 in main.c for r.water.outlet (see <a href="http://trac.osgeo.org/grass/browser/grass/trunk/raster/r.water.outlet/main.c" target="_blank">http://trac.osgeo.org/grass/browser/grass/trunk/raster/r.water.outlet/main.c</a>):</div>
<div><br></div><div> if (window.east > 180 && G_projection()==3){</div><div> E = E+360;</div><div> }</div><div><br></div><div>Or, if I understand G_adjust_easting(), then we might be able to skip all of that and simply type:</div>
<div><br></div><div> E = G_adjust_east_longitude(E,window.west);</div><div><br></div><div>Sound like a good improvement?</div><div><br></div><font color="#888888"><div>Andy</div></font><div><div></div><div>
<br><br><div class="gmail_quote">On Sat, Jul 2, 2011 at 2:16 AM, Andy Wickert <span dir="ltr"><<a href="mailto:wickert@colorado.edu" target="_blank">wickert@colorado.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>Made some progress on this myself; think that a solution will require some minor source code modifications.</div><div><br></div><div>The main idea and my question to GRASS users/developers:</div><div><br></div>I think that I better understand the r.water.outlet problem now. Briefly, I think a proper solution would require changing the r.water.outlet source code to deal with wraparound at the 180 meridian; as it stands, the code seems to be designed for northing/easting in projected coordinate systems. I'd be happy to change / recompile / test the source code; in that case, should I take this thread to the GRASS-dev list? I have found the programmer's manual, but if anyone has advice on how to start in on development in GRASS, I would greatly appreciate it.<div>
<br></div><div>Slightly more info:</div><div><br></div><div>I was able to make all the points work by specifying the window as W:-180, E:180. However, the drainage basins refused to cross the 180 meridian. I am fairly sure that these are because (1) I need increasing Easting values to make r.water.outlet work, but (2) in order to provide continously increasing Easting values, I must make a discontinuity at the 180 meridian in the middle of my data set. This makes me think that if I changed main.c inside r.water.outlet to include G_adjust_easting() within some if statments (is lat/long projection & West value is greater than East), that this would solve the problem.</div>
<div><br></div><div>The workaround, of course, is to shift all location references by 180 degrees, perform calculations, and move everything back, but I'd like to try to make a more elegant/permanent solution.</div><div>
<br></div><font color="#888888"><div>Andy</div></font><div><div></div><div><div><br></div><div><br><div><div class="gmail_quote">On Tue, Jun 28, 2011 at 11:43 AM, Andy Wickert <span dir="ltr"><<a href="mailto:wickert@colorado.edu" target="_blank">wickert@colorado.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">OK - I think I figured out some of it. On my computer where r.water.outlet DOES work, the west-longitudes are expressed as negative 0-180, while on the computer where it doesn't work, they are expressed as positive east-longitude 180-360.<div>
<br></div><div>So: the question becomes, how do I choose how west-longitudes are interpreted by GRASS?<br>
<br>Thanks!</div><div><br></div><font color="#888888"><div>Andy</div></font><div><div></div><div><div><br></div><div><br><div class="gmail_quote">On Mon, Jun 27, 2011 at 11:00 PM, Andy Wickert <span dir="ltr"><<a href="mailto:wickert@colorado.edu" target="_blank">wickert@colorado.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>Hi GRASS user-list,</div><div><br></div><div>I think that I have run into a bug in either the computational window definition or the r.water.outlet program (or maybe something else) that has to do with defining degrees West as either positive (East-longitude >180) or negative.</div>
<div><br></div><div>What happens is that, for example, I type:</div><div>r.water.outlet drainage=$watershed_direction basin=temp_basin easting=196 northing=60 --verbose --overwrite</div><div><br></div><div>And GRASS returns:</div>
<div><div>WARNING: Warning, ignoring point outside window:</div><div> -164.0000,60.0000</div></div><div><br></div><div>This occurs no matter whether I specify the longitude as a positive East-longitude (as above), as a negative value (e.g.,-164), or as, e.g., 164W. (196E is not allowed).</div>
<div><br></div><div>The problem is not my window definition, which includes the point in question:</div><div><div>proj: 3</div><div>zone: 0</div><div>north: 73:00:30N</div><div>south: 49:59:30N</div>
<div>east: 144:59:30W</div><div>west: 162:59:30E</div><div>cols: 3121</div><div>rows: 1381</div><div>e-w resol: 0:01</div><div>n-s resol: 0:01</div><div>top: 1</div><div>bottom: 0</div>
<div>cols3: 3121</div><div>rows3: 1381</div><div>depths: 1</div><div>e-w resol3: 0:01</div><div>n-s resol3: 0:01</div><div>t-b resol: 1</div></div><div><br></div><div>When I use r.what, it gives me East-longitudes (values >180) for regions to the East of the 180 meridian. But r.water.outlet insists on switching everything to negatives no matter what input I give it, which I think is a source of the problem.</div>
<div><br></div><div>The strangest thing about this is that I ran into this problem while following a routine that I had written several months ago in Bash; last time, I ran r.water.outlet on North America (all in degrees-west land) with no problems at all. I just checked the computational region (window) files for that run, and they look very similar to the ones I am using now. I have no clue why I didn't run into this problem back then / why it is cropping up now; both computers are running GRASS 6.4.1 on Ubuntu Linux.</div>
<div><br></div><div>Anyway, if anyone has any suggestions, I'm all ears. Many thanks in advance,</div><div><br></div><font color="#888888"><div>Andy Wickert</div>
</font></blockquote></div><br></div>
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</div></div></blockquote></div><br>
</div></div></blockquote></div><br></div></div></div>
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