[GRASS-user] using a vector map as target map for raster map to georectify

[Markus Metz]

On Mon, Oct 31, 2011 at 1:27 PM, Moritz Lennert
<mlennert at club.worldonline.be> wrote:
> On 31/10/11 11:34, Markus Metz wrote:
>>
>> On Mon, Oct 31, 2011 at 11:22 AM, Moritz Lennert
>> <mlennert at club.worldonline.be>  wrote:
>>>
>>> On 31/10/11 10:08, Markus Metz wrote:
>>>>
>>>>
>>>> On Sat, Oct 29, 2011 at 11:25 AM, Moritz Lennert
>>>> <mlennert at club.worldonline.be>    wrote:
>>>>>
>>>>>
>>>>> On 27/10/11 21:10, Moritz Lennert wrote:
>>>>>>
>>>>>>
>>>>>> Hello,
>>>>>>
>>>>>> Trying to use the georeferencing tool in 6.4.1, I have the following
>>>>>> question: is it possible to define a vector map as target map when
>>>>>> georeferencing a raster map ? I can't seem to find how to do this.
>>>>>
>>>>>
>>>>> Just to be precise: I'm talking about the tool in the wxgui.
>>>>>
>>>>> Am I the only one seeing this as a problem ? I can work around this by
>>>>> transforming my vector map in a raster and then use the result as
>>>>> target
>>>>> map. But I find this less than ideal. It should be possible to use
>>>>> vector
>>>>> map as reference, not only raster maps.
>>>>>
>>>>> I will file a bug report about this, but was just wondering whether I'm
>>>>> missing something obvious.
>>>>
>>>>
>>>> Vector support in the georeferencing tool is poor. Ideally the tool
>>>> would have something like a layer manager where you can add as
>>>> reference maps any number and combination of raster and vector maps,
>>>> just like in the regular layer manager. Further more, the C module
>>>> v.rectify is still missing (I want to write it based on v.transfrom
>>>> and v.proj but did not get around yet to do it).
>>>
>>>
>>> Ok, so currently I have to use the v.to.rast workaround, then. But does
>>> the
>>> solution really have to be a whole layer manager ? Generally one does not
>>> use many different layers as reference maps, so just having a choice
>>> between
>>> vector and raster reference maps in the preparatory steps of the tool
>>> should
>>> be enough IMHO.
>>
>>
>> OK. Then the option for reference maps could be one raster map and/or
>> one vector map (vector map always on top of raster map).
>
>
> This sounds good to me.
>
>
>>>
>>> v.rectify is still another issue. v.transform probably covers most of the
>>> use cases anyway, or ?
>>
>>
>> Yes, apart from the case when source and target LOCATION_NAME are
>> different. This is handled by v.proj. Since GCPs are specific for a
>> given source / target location combination, a TARGET like for imagery
>> groups would also be needed.
>
>
> I think that in many cases you can import the data directly into your target
> location and run v.transform there. This is less the case for raster data.
> But I agree that the possibility should be there for the user to
> georeference vector data between two different locations.

I have added full vector support in the wx georectifier (trunk
r50059). You can now display a vector and/or a raster from the target
location, and the long-standing bug [1] for vector rectification is
also fixed by using the new module v.rectify.

Markus M

[1] https://trac.osgeo.org/grass/browser/grass/branches/releasebranch_6_4/gui/wxpython/gui_modules/gcpmanager.py#L1408