[GRASS-dev] [GRASS GIS] #608: GIS.m: Lat/Lon support broken in Map Display zooms

GDAL · May 19, 2009, 2:35pm

#608: GIS.m: Lat/Lon support broken in Map Display zooms
-----------------------+----------------------------------------------------
Reporter: hamish | Owner: grass-dev@lists.osgeo.org
Type: defect | Status: new
Priority: blocker | Milestone: 6.4.0
Component: Tcl | Version: 6.4.0 RCs
Keywords: gis.m, LL | Platform: All
Cpu: All |
-----------------------+----------------------------------------------------
Hi,

when in a lat/lon location the gis.m Map Display zooming is quite broken.
Previously you'd get many "Error setting region: child process exited
abnormally [ok]" popping up*, and if you zoom out to the global scale
everything pretty much goes haywire.

[*] because `g.region n=$mapcanvas_value>90`

there's a partial fix in SVN now (r37285) -- it will switch into
constrained mode if you try to zoom out beyond 90 degrees N,S. But it's
not quite right, you still get white borders and the canvas coords get all
messed up after that. I expect that besides switching to constrained mode
it needs to either recalc the resolution after resetting N,S to 90, or
just break out of the routine it's in because the premise for being there
becomes invalid.

I've taken it about as far as I can go.
???

Hamish

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/608>
GRASS GIS <http://grass.osgeo.org>

GDAL · September 11, 2009, 5:24am

#608: GIS.m: Lat/Lon support broken in Map Display zooms
----------------------+-----------------------------------------------------
  Reporter: hamish | Owner: grass-dev@lists.osgeo.org
      Type: defect | Status: new
  Priority: blocker | Milestone: 6.4.0
Component: Tcl | Version: 6.4.0 RCs
Resolution: | Keywords: gis.m, LL
  Platform: All | Cpu: All
----------------------+-----------------------------------------------------
Comment (by cmbarton):

I'm not having any trouble with this using 6.4 compiled today (10
September 2009). I get a message about not being able to stay in "explore"
mode if you zoom out beyond the poles. But I can still zoom out and in and
get a map. No errors. The only oddity was that once I zoomed out beyond
the poles and tried to zoom in with a box, it centered the display in the
wrong place. If I just clicked, it zoomed in OK.

I'm doing this on a Mac.

Michael

--
Ticket URL: <http://trac.osgeo.org/grass/ticket/608#comment:1>
GRASS GIS <http://grass.osgeo.org>

GDAL · September 11, 2009, 8:33am

#608: GIS.m: Lat/Lon support broken in Map Display zooms
----------------------+-----------------------------------------------------
  Reporter: hamish | Owner: grass-dev@lists.osgeo.org
      Type: defect | Status: new
  Priority: blocker | Milestone: 6.4.0
Component: Tcl | Version: 6.4.0 RCs
Resolution: | Keywords: gis.m, LL
  Platform: All | Cpu: All
----------------------+-----------------------------------------------------
Comment (by hamish):

It will still be broken. (afaik no one has touched the code since I last
did).

from memory:
try with the etopo2 dataset or some 180E-180W, 90S-90N raster with a 15
degree d.grid overlay. adjust map box so you have white bands at the top
and bottom. zoom in, then zoom out and back out to global view. compare
the position shown on the status bar with what should be the value from
the grid lines. you will notice it counts as pixels from the top of the
map window, not from the bottom of the upper white >90N band.

Hamish

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/608#comment:2>
GRASS GIS <http://grass.osgeo.org>

GDAL · September 11, 2009, 3:52pm

#608: GIS.m: Lat/Lon support broken in Map Display zooms
----------------------+-----------------------------------------------------
  Reporter: hamish | Owner: grass-dev@lists.osgeo.org
      Type: defect | Status: new
  Priority: blocker | Milestone: 6.4.0
Component: Tcl | Version: 6.4.0 RCs
Resolution: | Keywords: gis.m, LL
  Platform: All | Cpu: All
----------------------+-----------------------------------------------------
Comment (by cmbarton):

Thanks for the additional info. I'll try this specific test and see what
happens.

Michael

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/608#comment:3>
GRASS GIS <http://grass.osgeo.org>

GDAL · September 15, 2009, 5:33am

#608: GIS.m: Lat/Lon support broken in Map Display zooms
----------------------+-----------------------------------------------------
  Reporter: hamish | Owner: grass-dev@lists.osgeo.org
      Type: defect | Status: closed
  Priority: blocker | Milestone: 6.4.0
Component: Tcl | Version: svn-develbranch6
Resolution: fixed | Keywords: gis.m, LL
  Platform: All | Cpu: All
----------------------+-----------------------------------------------------
Changes (by cmbarton):

* cc: hamish_b@yahoo.com (added)
  * status: new => closed
  * version: 6.4.0 RCs => svn-develbranch6
  * resolution: => fixed

Comment:

I think I've fixed this bug. Please test GRASS 6.5 svn R39213.

It does not crash and display and zooming work in both constrained and
unconstrained ("explore") modes. If you try repeatedly to zoom out beyond
the maximum latlon (i.e., beyond 90N or 90S), the behavior is
unpredictable. But it gives a clean error when it can no longer handle
zoom out beyond what is permissible.

Coordinates all seem to be accurate (i.e., the pointer seems to return the
correct coordinate), and coordinates beyond 180E become West, and vice
versa.

Please test. If it is satisfactory, it can be backported to 6.4.

Note that it seems that the wxpython display does not seem to suffer from
the latlon zooming bug, but functions pretty much as the fixed TclTk GUI
does now. That is, it is unpredictable if you try to zoom beyond the
maximum latlon, but otherwise works fine.

Michael

--
Ticket URL: <http://trac.osgeo.org/grass/ticket/608#comment:4>
GRASS GIS <http://grass.osgeo.org>

GDAL · September 15, 2009, 1:37pm

#608: GIS.m: Lat/Lon support broken in Map Display zooms
----------------------+-----------------------------------------------------
  Reporter: hamish | Owner: grass-dev@lists.osgeo.org
      Type: defect | Status: closed
  Priority: blocker | Milestone: 6.4.0
Component: Tcl | Version: svn-develbranch6
Resolution: fixed | Keywords: gis.m, LL
  Platform: All | Cpu: All
----------------------+-----------------------------------------------------
Changes (by hamish):

* cc: hamish_b@yahoo.com (removed)

Comment:

> If you try repeatedly to zoom out beyond the maximum latlon
> (i.e., beyond 90N or 90S), the behavior is unpredictable.

mmmph. that's what I was trying to address with the if(y>90)y=90; stuff.
Instead of that maybe it could just invoke pan mode or return with the
same bounds as it started with?

> Please test. If it is satisfactory, it can be backported to 6.4.

sure. I'm using the etopo2 dataset for testing. (see grass wiki global
datasets page)

fyi- if you are the reporter or have commented to the bug report you are
automatically added to the cc list. Also if adding to the cc list it is
better to use the osgeo ID than full email addr, as exposing that just
adds to the spam load..

thanks for taking this one on,
Hamish

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/608#comment:5>
GRASS GIS <http://grass.osgeo.org>

GDAL · September 15, 2009, 2:56pm

#608: GIS.m: Lat/Lon support broken in Map Display zooms
----------------------+-----------------------------------------------------
  Reporter: hamish | Owner: grass-dev@lists.osgeo.org
      Type: defect | Status: closed
  Priority: blocker | Milestone: 6.4.0
Component: Tcl | Version: svn-develbranch6
Resolution: fixed | Keywords: gis.m, LL
  Platform: All | Cpu: All
----------------------+-----------------------------------------------------
Comment (by cmbarton):

Good to know about the cc'ing. I don't know your OSGEO ID. Is there a
place to find this easily?

I wasn't very specific about what had changed in the zooming and will try
to explain more here.

When I started (at least on my system), any zoom out or panning raised a
g.region error. Full window ('explore') mode was turned off for latlon
locations because it raised an error when you tried to load the map. EW
coordinates could be far beyond 180 degrees.

Now, all coordinates seem correct. Full screen mode works as well as
constrained mode (maybe a bit better). All zooming and panning works with
the following 2 exceptions:

1) If you keep trying to zoom out beyond 90N, 90S, 180E, 180W with
constrained mode (and maybe in full screen mode if you do it some more),
it will produce a viewing region that is too small and the error "maximum
zoom in limit exceeded" is raised.

2) If you zoom out beyond the max geographic coordinates more than once,
the map view may not be what you were expecting (though I'm not sure what
a user who keeps doing this IS expecting). That is, it may not be centered
in the zoom out box, the displayed map may have an unexpected ht/width
geometry, or it may even seem to zoom IN a little. This seems more
pronounced in constrained mode than full-screen mode.

I do have it set to just pan if the map is at or attempts to go beyond the
max zoom out. However, we don't want this to take effect until the max
zoom out. So the slightest bit below the max coordinates and it goes back
to "normal" behavior. I could just have it return to the previous bounds
too, but it would still have the same issue. I'm assuming that sometimes
the user will want the map to show the entire world (i.e., max zoomout)
and might like it centered on different longitudes (i.e., other than 0
E/W) and have tried to preserve that possibility.

What seems to happen is that if you try to zoom out beyond bounds once, it
behaves well (i.e., goes into pan mode an shifts the center to be in the
zoom out box or at the pointer for one-click zoom out). If you keep doing
this, it begins to behave erratically and, with constrained mode,
eventually reaches a max zoom in error.

Hope that helps explain better where the functioning is at currently.

Michael

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/608#comment:6>
GRASS GIS <http://grass.osgeo.org>

neteler · September 15, 2009, 3:49pm

On Tue, Sep 15, 2009 at 4:56 PM, GRASS GIS <trac@osgeo.org> wrote:

Good to know about the cc'ing. I don't know your OSGEO ID.
Is there a place to find this easily?

Sure:
http://www.osgeo.org/cgi-bin/ldap_web_search.py

Markus

GDAL · September 16, 2009, 1:34pm

#608: GIS.m: Lat/Lon support broken in Map Display zooms
----------------------+-----------------------------------------------------
  Reporter: hamish | Owner: grass-dev@lists.osgeo.org
      Type: defect | Status: closed
  Priority: blocker | Milestone: 6.4.0
Component: Tcl | Version: svn-develbranch6
Resolution: fixed | Keywords: gis.m, LL
  Platform: All | Cpu: All
----------------------+-----------------------------------------------------
Comment (by hamish):

Replying to [comment:6 cmbarton]:
> Good to know about the cc'ing. I don't know your OSGEO ID.
> Is there a place to find this easily?

Yup, and it's right under your nose

{{{
#608: GIS.m: Lat/Lon support broken in Map Display zooms
----------------------+-----------------------------------------------------
   Reporter: hamish | Owner: grass-dev
             ^^^^^^^^
...
Comment (by cmbarton):
            ^^^^^^^^^^^
}}}

thanks for the thorough explanation of the new behavior. it sounds like it
is just about there. More once I've had the chance to try it out.

Hamish

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/608#comment:7>
GRASS GIS <http://grass.osgeo.org>

GDAL · September 16, 2009, 5:04pm

#608: GIS.m: Lat/Lon support broken in Map Display zooms
----------------------+-----------------------------------------------------
  Reporter: hamish | Owner: grass-dev@lists.osgeo.org
      Type: defect | Status: closed
  Priority: blocker | Milestone: 6.4.0
Component: Tcl | Version: svn-develbranch6
Resolution: fixed | Keywords: gis.m, LL
  Platform: All | Cpu: All
----------------------+-----------------------------------------------------
Comment (by cmbarton):

Duh!

I guess I didn't get enough coffee this morning...

Let me know what you think of the fixes. I have an alternate idea for
fixing this, but can't guarantee that it will give any better results,
especially after looking at the behavior in the wx GUI. Zoom out beyond a
width of 360 degrees is likely to always be squirrelly because the
coordinates wrap back around a cylindrical earth map rather than extend in
endlessly increasing/decreasing values as you expand east and west in a
projection like UTM.

Michael

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/608#comment:8>
GRASS GIS <http://grass.osgeo.org>