GEOTIFF EXAMPLES?

[Luis Sa]

Hello,

I changed the MAP tool in SBuilder so that we can:

a) place non-georeferenced images

In SB205 we were limited to the bitmap format. Now we can place BMP JPEG, GIF, PNG and TIFF.

b) place georeferenced images

In SB205 we could place a BMP with a companion TXT file. I will keep this but I am adding the possibility placing GeoTiff images.

c) place a georeferenced image from Yahoo maps with one or two clicks.

This seems possible but did not tried it yet.

d) place a georeferenced from Google maps with one or two clicks.

I am not sure if this is possible but I will give it a try.


The purpose of this post is related to b). I wrote the code to read the GeoTiff tags and to check if a given image has a geographic projection and uses the WGS84 datum. If so, the image is automatically placed in SBuilder without the need for calibration. I need some test images to test my code. The GeoTiff images that I got in the web are not of the "GCS_WGS_84" type. Could anyone send me small (if possible) images of this type? If I get responses I will post here to avoid you have the trouble to send me the images when I do not need them anymore.

Thanks in advance,

Luis

[José]

Hi, Luis

The images in CGIAR, reportedly, are referenced to WGS84 datum.
I suppose it's easy to you to download an 5 degress x 5 degres mosaic directly, since it's very big to send to you. available in: http://srtm.csi.cgiar.org/

<i>"The DEM files have been mosaiced into a seamless global coverage, and are available for download as 5 degree x 5 degree tiles, in geographic coordinate system - WGS84 datum."</i>



J.F.Lôbo

[ray]

Hi Lou;
might this tif of your help -

is on fs format - geo - wgs 84 - 3 m

http://www.fsproject.com/luis.tif

ray

[Luis Sa]

Hello,

José - I get a "out of memory" error when I try to open the 6000 x 6000 image. My PC has 1GB [:0] and the error appears in this line of code:
Dim image As Bitmap = New Bitmap("c:\lixo\z_35_5.tif")

Ray - Your image showed me that I need to check the starting of the TIF file to determine if it uses little-endian or big-endian byte
order. But I the image "gets calibrated" automatically [:)]

Thank you for your help,

Luis

[José]

Hi, Luis

There are some geotiff images in the FSX SDK (my path:
C:\Arquivos de programas\Microsoft Games\Microsoft Flight Simulator X SDK\SDK\Environment Kit\Terrain SDK\Resample Examples\SourceData).

I think you can explore them in your tests, since this should be the standard for FSX, certainly.

Best regards,


J.F.Lôbo

[ray]

Keep up the good work Lou !

ill be a Life Long customer of scenery builder ! [:D]

well worth the effort !

ray

[José]

Luis,

Estou escrevendo em Português, porque a mensagem é para você.

Baixei a imagem geotiff que lhe foi enviada pelo Ray e abri num programa que utilizo (GlobalMapper ou a versão free DLGV).

Também abri a imagem da MS, DeathValleyTif.tif, que está dando erro para você.

As duas imagens são diferentes quando abertas no GM.

A imagem da MS dá a leitura das alturas de cada pixel sob o mouse, diretamente, na barra de status, enquanto nenhuma informação sobre altura pode ser vista na imagem enviada pelo Ray.

As imagens da CGIAR também são interpretadas pelo GM do mesmo modo que DeathValleyTif.tif, ou seja, as alturas são exibidas na barra de status.

Não sei se essas informações podem ajudar, mas vou trasncrever as características da imagem DeathValleyTif.tif, mostradas pelo GM:

GeoTiff Tags:
-------------
Geographic (Latitude/Longitude)
DATUM: WGS84
UNIT: arc degrees
=================END

Metadata
--------
FILENAME=G:\FSX\ENVIRONMENT KIT\TERRAIN SDK\RESAMPLE EXAMPLES\SOURCEDATA\DEATHVALLEYTIF.TIF
DESCRIPTION=DEATHVALLEYTIF.TIF
UPPER LEFT X=-117.09986111
UPPER LEFT Y=36.39986111
LOWER RIGHT X=-116.60013889
LOWER RIGHT Y=36.00013889
WEST LONGITUDE=117° 05' 59.50" W
NORTH LATITUDE=36° 23' 59.50" N
EAST LONGITUDE=116° 36' 00.50" W
SOUTH LATITUDE=36° 00' 00.50" N
NUM COLUMNS=1800
NUM ROWS=1440
PIXEL WIDTH=0.00028 arc degrees
PIXEL HEIGHT=0.00028 arc degrees
MIN ELEVATION=-83.329 meters
MAX ELEVATION=3369.243 meters
ELEVATION UNITS=meters
=====================END

Vertical Metadata
-----------------
Vertical Units: meters
Minimum Elevation: -83.3286 meters
Maximum Elevation: 3369.24 meters
==================END

TIFF Metadata
-----------------
Photometric Interpretation : Greysacle (Min is Black)
Bits per pixel: 32
Image Length (pixels): 1440
Image Width (pixels): 1800
Rows Per Strip: 1
==================END



J.F.Lôbo

[José]

Luis,

I opened the other so called geotiff images from MS FS X SDK "Environment Kit\Terrain SDK\Resample Examples\SourceData" and only the DeathValleyTif.tif image has geotiff characteristics.

Perhaps, the word "Tif" at the end of its name means that.

Thanks,

José

J.F.Lôbo

[Luis Sa]

Hello José,

Thank you for your attention. I had already came to the same conclusion as you. The DeathValleyTif.tif is clearly a GeoTiff image. SBuilder detects it by reading both TIFF tags and Geotiff keys. Form these tags/keys SBuilder (if the tags indicate a geographical projection and the WGS84 datum) calculates the north, south, west and east borders which allows for an automatic placing of the image without "calibration".

There is a tag that indicates if the image has "Z data = altitude". I am not reading that tag and that is because that Sbuilder fails to show it as a normal image. I left the problem on standby and now I am dealing with the SHAPEFILE import/export (yesterday I was able to have something working [:)]). When I look to the Geotiff problem again I have to decide how to represent altitude data. Perhaps I will look to "my personnal" format used in SBuilder 2.05 or I will have to use something like GlobalMapper.

Saudações,

Luis

[José]

Hi, Luis

When you go back to geotiff, please, don't forget to review the CGIAR images (they are geotiff, really), the ones that generated errors when you tried to open.

Best regards,

JOsé

J.F.Lôbo