[GRASS-user] assign heigght value to pixel(x,y)

[vinod kumar]

Hi Sylvain Maillard,

It means that we cannot obtain 3d from raster (orthophoto) and for that we
need to build block of data in a 3Dimensional using some graphic software ,
right?

One more question, i am not having vector layer and i need to create from
raster and intrestingly i am having cadastral layer  with attributes(height
of buildings).

So i am planning to create grid, triangulate and assign heights to the
buildings.

And with cadastral data information and raster data, can we create DTM and
export those values into VRML or X3d formats.

Thanks in advance,
nani.


On Mon, Apr 18, 2011 at 9:13 AM, vinod kumar <nani.kunithi at gmail.com> wrote:

> Hi Sylvain Maillard,
>
> Thanks for providing the information on creating separating vector layer to
> assign height but how to make 3Dimensional layer for the raster with
> accurate weightage value to each pixel.
>
> Thanks in advance,
> nani
>
>
> On Sun, Apr 17, 2011 at 10:56 PM, Sylvain Maillard <
> sylvain.maillard at gmail.com> wrote:
>
>> Hi,
>>
>> i'm not sure that the raster way is the easiest, the tools are not really
>> usable for what you want to do ...
>>
>> you better have to make a new vector layer with a "height" attribute, then
>> display it over your raster and edit the vector layer by drawing
>> polygon/point with the height as attibute. Once ended, you will have to
>> convert the vector to raster (v.to.rast) using the attribute "height" as
>> raster value.
>> I think it's the easiest way as you will be able to store the same height
>> for many consecutive pixel without having to edit each one, and you will
>> also be able to easily change the height if your first try is not good
>> enought ;)
>>
>>
>>
>> cheers,
>>
>> Sylvain
>>
>>
>> 2011/4/17 vinod kumar <nani.kunithi at gmail.com>
>>
>>> Hi Markus Netler,
>>>
>>> i want to identify buildings, trees etc.. and assign height values at
>>> particular zoom level in a raster map and to view the data in a 3Dimensional
>>> where i do not have any information to identify pixel graphically.
>>>
>>> And the problem also persists in identifying buildings and assigning
>>> height values and to use condition like IF might not be possible as there is
>>> no source of information.
>>>
>>> Thanks in advance,
>>> nani.
>>>
>>>
>>>
>>> On Sat, Apr 16, 2011 at 11:06 PM, Markus Neteler <neteler at osgeo.org>wrote:
>>>
>>>> On Sat, Apr 16, 2011 at 10:36 PM, vinod kumar <nani.kunithi at gmail.com>
>>>> wrote:
>>>> > Hi Markus Neteler,
>>>> >
>>>> > yes, importing pixel values with r.in ascii and patch into existing
>>>> into
>>>> > raster is simple easy for particular pixel,
>>>> > but if we want to assign a height value to more pixels, for example
>>>> > assigning height value to buildings in a
>>>> > particular area in raster map is difficult as we don't no to which
>>>> pixel
>>>> > value we have to assign height value and
>>>> > checking each pixel value is difficult.
>>>>
>>>> Now I understand a bit more: so use r.mapcalc with an if() condition.
>>>>
>>>> Markus
>>>>
>>>
>>>
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>>>
>>
>
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