ImageElevationHandler

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ImageElevationHandler

Guillaume Pasero
Hi,

I have a question about the ossimImageElevationHandler :
- is there an expected projection for the images given to this handler ?

I have tried with GeoTIFF DEMs in geographic projections (epsg 4326 and
4269), the result is fine.
I have tried with GeoTIFF DEM projected in UTM (epsg , units in meter),
the result is slow to process and identic to the case without any DEM.

Regards,
Guillaume

--
<www.c-s.fr> *Guillaume PASERO*
Ingénieur d'études et développement
*Business Unit E-SPACE & Geo Information*
<https://thor.si.c-s.fr/blogs/cs-blogs-business/>*- Département
APPLICATIONS*

*CS Systèmes d'Information*
Parc de la Grande Plaine - 5, Rue Brindejonc des Moulinais - BP 15872
31506 Toulouse Cedex 05 - FRANCE
+33 561 17 64 21 - [hidden email]


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Re: ImageElevationHandler

DBurken@Radiantblue.com
Are the tiff formats the same for both dems.  Are they both tiled
tiffs?  Not sure if that would make a difference or not.  You can do:

ossim-info -d <tiff>

To see the tags.

Take care,
Dave


On 12/14/2015 05:33 AM, Guillaume Pasero wrote:

> Hi,
>
> I have a question about the ossimImageElevationHandler :
> - is there an expected projection for the images given to this handler ?
>
> I have tried with GeoTIFF DEMs in geographic projections (epsg 4326 and
> 4269), the result is fine.
> I have tried with GeoTIFF DEM projected in UTM (epsg , units in meter),
> the result is slow to process and identic to the case without any DEM.
>
> Regards,
> Guillaume
>


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Re: ImageElevationHandler

Guillaume Pasero
Hi,

All dems have the same type : stripped, same size, same pixel type. For
the UTM one, I get :
tiff.version: 42(classic)
tiff.byte_order: little_endian
tiff.directory_offset: 8
tiff.image0.image_width: 1201
tiff.image0.image_length: 1201
tiff.image0.bits_per_sample: 16
tiff.image0.compression: false
tiff.image0.photo_interpretation: MINISBLACK
tiff.image0.samples_per_pixel: 1
tiff.image0.rows_per_strip: 3
tiff.image0.planar_configuration: single image plane
tiff.image0.sample_format: 2
tiff.image0.sample_format_string: signed integer data
tiff.image0.model_pixel_scale: 0.961698584512906 0.93255620316403 0
tiff.image0.model_tie_point: 0 0 0 369780.480849292 4827019.5337219 0
tiff.image0.gdalmetadata.unittype:m
tiff.image0.gdal_nodata: -32768
tiff.image0.model_type: projected
tiff.image0.raster_type: pixel_is_point
tiff.image0.citation: WGS 84 / UTM zone 31N|
tiff.image0.geographic_citation: WGS 84|
tiff.image0.angular_units_code: 9102
tiff.image0.angular_units: degrees
tiff.image0.pcs_code: 32631
tiff.image0.linear_units_code: 9001
tiff.image0.linear_units: meters

I have tried to convert the UTM DEM into a tiled Tiff but same result.
tiff.image0.tile_width: 256
tiff.image0.tile_length: 256

I have noticed that ossimImageElevationHandler uses the method
'm_geom->worldToLocal(gpt, dpt)' to reproject positions into image. Is
the 'world' supposed to be in WGS84 lon/lat coordinates or is it the
coordinate system of the image loaded ?

Regards,
Guillaume


On 12/14/2015 01:23 PM, [hidden email] wrote:

> Are the tiff formats the same for both dems.  Are they both tiled
> tiffs?  Not sure if that would make a difference or not.  You can do:
>
> ossim-info -d <tiff>
>
> To see the tags.
>
> Take care,
> Dave
>
>
> On 12/14/2015 05:33 AM, Guillaume Pasero wrote:
>> Hi,
>>
>> I have a question about the ossimImageElevationHandler :
>> - is there an expected projection for the images given to this handler ?
>>
>> I have tried with GeoTIFF DEMs in geographic projections (epsg 4326 and
>> 4269), the result is fine.
>> I have tried with GeoTIFF DEM projected in UTM (epsg , units in meter),
>> the result is slow to process and identic to the case without any DEM.
>>
>> Regards,
>> Guillaume
>>
>
>

--
<www.c-s.fr> *Guillaume PASERO*
Ingénieur d'études et développement
*Business Unit E-SPACE & Geo Information*
<https://thor.si.c-s.fr/blogs/cs-blogs-business/>*- Département
APPLICATIONS*

*CS Systèmes d'Information*
Parc de la Grande Plaine - 5, Rue Brindejonc des Moulinais - BP 15872
31506 Toulouse Cedex 05 - FRANCE
+33 561 17 64 21 - [hidden email]


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Re: ImageElevationHandler

DBurken@Radiantblue.com
Yes, lat/lon. The geometry model will convert utm to lat/lon.   So
that's a dense dem, i.e. .9 meters.  Would need to profile it. Might
need to do a cache for that elevation handler.  If you see anything that
stands out let us know.

Dave

On 12/14/2015 08:50 AM, Guillaume Pasero wrote:

> Hi,
>
> All dems have the same type : stripped, same size, same pixel type. For
> the UTM one, I get :
> tiff.version: 42(classic)
> tiff.byte_order: little_endian
> tiff.directory_offset: 8
> tiff.image0.image_width: 1201
> tiff.image0.image_length: 1201
> tiff.image0.bits_per_sample: 16
> tiff.image0.compression: false
> tiff.image0.photo_interpretation: MINISBLACK
> tiff.image0.samples_per_pixel: 1
> tiff.image0.rows_per_strip: 3
> tiff.image0.planar_configuration: single image plane
> tiff.image0.sample_format: 2
> tiff.image0.sample_format_string: signed integer data
> tiff.image0.model_pixel_scale: 0.961698584512906 0.93255620316403 0
> tiff.image0.model_tie_point: 0 0 0 369780.480849292 4827019.5337219 0
> tiff.image0.gdalmetadata.unittype:m
> tiff.image0.gdal_nodata: -32768
> tiff.image0.model_type: projected
> tiff.image0.raster_type: pixel_is_point
> tiff.image0.citation: WGS 84 / UTM zone 31N|
> tiff.image0.geographic_citation: WGS 84|
> tiff.image0.angular_units_code: 9102
> tiff.image0.angular_units: degrees
> tiff.image0.pcs_code: 32631
> tiff.image0.linear_units_code: 9001
> tiff.image0.linear_units: meters
>
> I have tried to convert the UTM DEM into a tiled Tiff but same result.
> tiff.image0.tile_width: 256
> tiff.image0.tile_length: 256
>
> I have noticed that ossimImageElevationHandler uses the method
> 'm_geom->worldToLocal(gpt, dpt)' to reproject positions into image. Is
> the 'world' supposed to be in WGS84 lon/lat coordinates or is it the
> coordinate system of the image loaded ?
>
> Regards,
> Guillaume
>
>
> On 12/14/2015 01:23 PM, [hidden email] wrote:
>> Are the tiff formats the same for both dems.  Are they both tiled
>> tiffs?  Not sure if that would make a difference or not.  You can do:
>>
>> ossim-info -d <tiff>
>>
>> To see the tags.
>>
>> Take care,
>> Dave
>>
>>
>> On 12/14/2015 05:33 AM, Guillaume Pasero wrote:
>>> Hi,
>>>
>>> I have a question about the ossimImageElevationHandler :
>>> - is there an expected projection for the images given to this handler ?
>>>
>>> I have tried with GeoTIFF DEMs in geographic projections (epsg 4326 and
>>> 4269), the result is fine.
>>> I have tried with GeoTIFF DEM projected in UTM (epsg , units in meter),
>>> the result is slow to process and identic to the case without any DEM.
>>>
>>> Regards,
>>> Guillaume
>>>
>>


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