[GRASS-dev] Re: [GRASS GIS] #163: g.transform no longer calculating error for 2nd order transformation

[Michael Barton]

On 6/17/08 6:03 AM, "Martin Landa" <landa.martin at gmail.com> wrote:

> Hi Michael,
> 
>> Yes. This has 6 points like it is supposed to. But the transformation
>> doesn't work. Doesn't work with more than 6 either.
> 
> from
> 
> g.transform g=roads_streams o=2 f=src,dst,rev,fwd,fd,rd
>  274.000000 462.000000 598064.018692 4927655.934580 274.000000
> 462.000000 598064.018692 4927655.934580 0.000000 0.000000
>  ....
> 
> I get what I would expect with min number of GPSs for the given order,
> when I add some other GPSs to the points file I get non-zero fwd/rev
> errors
> 

I haven't tried this in a couple of weeks, but when I ran this with a
current build a free weeks ago, I only got 0's here. You are getting values,
but I got nothing.

> g.transform g=roads_streams o=2
>  0.004227 0.007915
>  0.132068 0.006500
>  0.047218 0.003247
> ...
> 
> Maybe I don't understand your point here,


I don't know if this is a function of something that is now fixed, or a
problem with the Mac.

Michael

> 
> Regards, Martin
> 
> 2008/6/17 Michael Barton <michael.barton at asu.edu>:
> 
>> 
>> Michael
>> 
>> 
>> On 6/17/08 3:44 AM, "GRASS GIS" <trac at osgeo.org> wrote:
>> 
>>> #163: g.transform no longer calculating error for 2nd order transformation
>>> -----------------------+----------------------------------------------------
>>>   Reporter:  cmbarton  |       Owner:  grass-dev at lists.osgeo.org
>>>       Type:  defect    |      Status:  new
>>>   Priority:  major     |   Milestone:  6.3.1
>>>  Component:  default   |     Version:  svn-develbranch6
>>> Resolution:            |    Keywords:  g.transform georectify
>>> -----------------------+----------------------------------------------------
>>> Comment (by martinl):
>>> 
>>>  Replying to [ticket:163 cmbarton]:
>>>> Sometime recently, g.transform stopped calculating forward and backward
>>>  error for 2nd order transformations. It simply returns 0's. 1st order
>>>  transformations still work fine AFAICT.
>>> 
>>>  The 2nd order transformations requires at least 6 GCPs. Your input POINTS
>>>  file contains 6 points. Then forward/reverse error is 0.0's.
>>> 
>>>  Martin
>> 
>> __________________________________________
>> Michael Barton, Professor of Anthropology
>> Director of Graduate Studies
>> School of Human Evolution & Social Change
>> Center for Social Dynamics & Complexity
>> Arizona State University
>> 
>> phone: 480-965-6213
>> fax: 480-965-7671
>> www: http://www.public.asu.edu/~cmbarton
>> 
>> 
>> 
> 
> 

__________________________________________
Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton