[GRASSLIST:7952] Re: r.proj takes a very long time / does not complete

[Ian MacMillan]

A rule of thumb that I use is that 1 arc-second equals 30 meters.  This 
is close enough for the work that I do.  It varies away from the 
equator, and I am not sure if it is exactly 30 meters, it probably 
depend on the type of ellipsoid used for the earth.  Hope this helps.

-Ian


On Aug 17, 2005, at 11:41 AM, Jason Horn wrote:

> Ian, Morten,
>
> Thanks so much for pointing out the problem.  I have seceded in 
> projecting the raster layer, with the help of the v.in.region box 
> trick.  I have set the resolution to an approximation of what I think 
> is right.  However, how can I really match the resolution in the new 
> state plane location to the resolution from the old lat-lon location?
>
> - Jason
>
>
> On Aug 15, 2005, at 5:25 PM, Ian MacMillan wrote:
>
>> A simple way to do this is to make a vector box of your region in the 
>> first location using v.in.region.  Go to your new location, v.proj 
>> that vector in, and set your region to the new vector.  Then use 
>> r.proj on the raster you want to project.  You will still have to set 
>> the resolution on your own though.  Hope this makes sense.
>>
>> -Ian
>>
>> On Aug 15, 2005, at 2:14 PM, Morten Hulden wrote:
>>
>>
>>>
>>>
>>> No wonder it takes forever. Your output location has 527482690275 
>>> cells (847325 x 622527) to project.
>>>
>>> You should adjust the boundaries or resolution of your NAD83 
>>> location to something more reasonable. Before running r.proj try to 
>>> set a resolution value that roughly matches the resolution of your 
>>> input map (g.region res= ), e.g. something like 1000 m.
>>>
>>> Don't know about boundaries for your location (TX unknown area to 
>>> me) but you may want to check those as well. No need to cover more 
>>> than what is necessary.
>>>
>>> rgds
>>> Morten
>>>
>>>
>>> Jason Horn wrote:
>>>
>>>> Morten,
>>>> Thanks for looking at this for me.  Below are the files you asked 
>>>> for.
>>>> PROJ_INFO for the source lat-lon location:
>>>> name: Latitude-Longitude
>>>> datum: wgs84
>>>> towgs84: 0.000,0.000,0.000
>>>> proj: ll
>>>> ellps: wgs84
>>>> cellhd file for  KEWX20040710_025420:
>>>> proj:       3
>>>> zone:       0
>>>> north:      34:00:17.832478N
>>>> south:      25:11:59.799175N
>>>> east:       92:43:25.599215W
>>>> west:       103:19:56.000785W
>>>> cols:       1000
>>>> rows:       830
>>>> e-w resol:  0:00:38.190402
>>>> n-s resol:  0:00:38.190402
>>>> format:     -1
>>>> compressed: 1
>>>> PROJ_INFO file for the destination NAD83 location:
>>>> name: Lambert Conformal Conic
>>>> datum: nad83
>>>> towgs84: 0.000,0.000,0.000
>>>> proj: lcc
>>>> ellps: grs80
>>>> a: 6378137.0000000000
>>>> es: 0.0066943800
>>>> f: 298.2572221010
>>>> lat_0: 31.1666670000
>>>> lat_1: 27.4166670000
>>>> lat_2: 34.9166670000
>>>> lon_0: -100.0000000000
>>>> x_0: 1000000.0000000000
>>>> y_0: 1000000.0000000000
>>>> WIND file for the destination NAD83 location:
>>>> proj:       99
>>>> zone:       0
>>>> north:      1196061
>>>> south:      573534
>>>> east:       1563147
>>>> west:       715822
>>>> cols:       847325
>>>> rows:       622527
>>>> e-w resol:  1
>>>> n-s resol:  1
>>>> top:        1
>>>> bottom:     0
>>>> cols3:      847325
>>>> rows3:      622527
>>>> depths:     1
>>>> e-w resol3: 1
>>>> n-s resol3: 1
>>>> t-b resol:  1
>>>> Thanks again!
>>>> - Jason
>>>> On Aug 13, 2005, at 12:14 PM, Morten Hulden wrote:
>>>>
>>>>> Jason Horn wrote:
>>>>>
>>>>>
>>>>>> I have a long-standing problem with r.proj.  I have never been  
>>>>>> able to complete a successful re-projection of a raster file.  
>>>>>> For  example, I am trying to pull in a raster file from a 
>>>>>> location that  is lat-lon, WGS84 into a location that is 
>>>>>> state-plane meters,  NAD83.  The raster grid is relatively small, 
>>>>>> 1000 cols by 830  rows.  I start r.proj like this:
>>>>>> r.proj input=KEWX20040710_025420 location=TX_ll_WGS84  
>>>>>> mapset=PERMANENT output=proj1 method=nearest Although my CPU 
>>>>>> stays  pegged at close to 100% usage, the progress bar never 
>>>>>> moves  forward and nothing happens, even if I leave it for many 
>>>>>> hours.   Can anyone tell me what's going on here?
>>>>>>
>>>>>>
>>>>>
>>>>> In order to help you I would like to see:
>>>>>
>>>>> 1) The PROJ_INFO file for your latlon location
>>>>> 2) The cellhd file of the KEWX20040710_025420 map in the latlon  
>>>>> location
>>>>> 3) The PROJ_INFO file for your NAD83 location
>>>>> 4) The WIND file for your NAD83 location
>>>>>
>>>>>
>>>>>
>>>>>
>>>
>>>
>>
>>
>>
>
>
What happens if a big asteroid hits Earth? Judging from realistic 
simulations involving a sledge hammer and a common laboratory frog, we 
can assume it will be pretty bad.
  - Dave Barry


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