[GRASS-dev] Struggling using two layered vector maps with v.what.rast

[Sören Gebbert]

Hi

[snip]
> Not so hard ;) But with thousands of vector layers you could
> experience slowed down operations involving categories, slowed down
> exponentially with the number of layers. But maybe this only becomes
> an issue with hundreds of thousands of vector layers.

Done in r50501
https://trac.osgeo.org/grass/changeset/50501

Best regards
Soeren

>>
>> btw:
>> * v.timestamp with layer support is in svn
>> * Vector layer timestamp support in the temporal GIS implementation is
>> in my local svn copy and   needs more testing -> i need to create
>> vector maps with multiple categorized layer.
>
> For the time being, you could run v.category option=transfer in a loop.
>
> Markus M
>
>>>
>>>> Additionally i need to
>>>> timestamp the layer in the temporal database. It would be meaningful
>>>> to timestamp layers at file level using v.timestamp too.
>>>> An approach which i have in mind is to extent v.timestamp with a layer
>>>> option, so that timetsamp text files can be created for each layer in
>>>> the vector map directory.
>>>>
>>>> An application in the temporal GIS and for environmental modelling
>>>> would be the observation of raster time series at specific vector
>>>> point locations. The vector location do not change over time, but the
>>>> attribute tables. Hence, for each observed time step a new timestamped
>>>> layer and table will be added to the observation vector map and filled
>>>> with raster values.
>>>>
>>>>>
>>>>>>
>>>>>>  i just started to investigate the
>>>>>> new shiny world of multiple layer usage.
>>>>>
>>>>> I hope you enjoy it!
>>>>
>>>>  I do. :)
>>>>
>>>> Best regards
>>>> Soeren
>>>>
>>>>>
>>>>> Markus M
>>>>>
>>>>>>
>>>>>> Best regards
>>>>>> Soeren
>>>>>>
>>>>>> 2012/1/25 Martin Landa <landa.martin at gmail.com>:
>>>>>>> Hi,
>>>>>>>
>>>>>>> db.copy from_table=soil to_table=soil_2
>>>>>>>
>>>>>>> -> makes copy of `soil` table
>>>>>>>
>>>>>>> v.db.addtable map=soil table=soil_2 layer=2
>>>>>>>
>>>>>>> -> it would overwrite `soil_2` table, but do nothing in this case, no
>>>>>>> feature have category defined in layer 2.
>>>>>>>
>>>>>>> Proposal:
>>>>>>>
>>>>>>> v.random --o -z seed=1 output=soil n=20 zmin=0 zmax=100 column=clay
>>>>>>> v.category input=soil out=soil2 option=transfer layer=1,2 --o
>>>>>>> db.copy from_table=soil to_table=soil_2
>>>>>>> v.db.connect map=soil2 table=soil_2 layer=2
>>>>>>>
>>>>>>> v.db.addcolumn map=soil2 layer=1 columns='sand_frac DOUBLE PRECISION'
>>>>>>> v.db.addcolumn map=soil2 layer=2 columns='sand_frac DOUBLE PRECISION'
>>>>>>> ...
>>>>>>>
>>>>>>> Martin
>>>>>>>
>>>>>>> --
>>>>>>> Martin Landa <landa.martin gmail.com> * http://geo.fsv.cvut.cz/~landa
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