Standards Forum

Retrieving models from a CDB for a particular tile

2011-05-13T05:10:45-05:00

Hi,

I am using the CDB API to fetch data from a CDB.
I am able to read the raster and vector data through the respective interfaces.
My question now is on the 3dModel interface.

For a given tile, if I have to find and extract all the 3D objects/models in that tile
How can I achieve this. Can someone provide some examples code snippets or direct me accordingly.

I have created a CDB with miltiple vector points in a tile and mapped all vector points to a tree (pointing to an openflight model), The openflight model for tree is located in CDBGTModel.

Now using the API how do I find the 3d models that are placed in a particular tile.

Thanks.

-Rushoth

CDB.xml

2010-01-20T12:23:06-05:00

Currently I am testing the CDB api, but I have a problem. When I try to load a specific flt (like D500_S001_T001_EC030_025_Pine-Tree01.flt) I need the FSC code (in this case 025) but I look for it in the CDB.xml file, and I can not find it, of course I can find it in the Apendix N, but I would like to read it from a xml, or something like that. Could you tell me how the CDB.dll knows the FSC code?

3D Model Textures

2009-07-31T11:52:45-05:00

I am currently trying to load a geospecific model using the cdb api and am unsure of how the texture part is supposed to work.
In my test cdb I get something similar to the following when querying the 3d model for a texture name
../../../301_GSModelTexture/L07/U15/N00E000_D301_S001_T001_L07_U15_R79_TEX03.rgb

How should I be going from this to loading the texture? The model seems to have been saved with relative paths and I guess that it should have been saved with no paths but that isn’t a problem.
Should I be decomposing the string so that I can construct a cdbDB::fileParams to load the texture or is there something wrong with the texture name in my cdb?

Also should the texture name I pass in to cdDB::fileParams::m_acTexture be TEX03 or TEX03.rgb? It can’t be the long filename because it exceeds the 32 bytes allocated to the string.

CDB Availability

2009-09-08T04:40:34-05:00

Why is it necessary to purchase Presagis products in order to obtain and use the CDB API? Equivalent open formats, such as SEDRIS and Collada, provide free APIs which seems appropriate for open standards and helps encourage take-up and wider usage by the community. Thanks.

Unicode Build

2009-07-24T09:10:58-05:00

When trying to compile a test app in a unicode build I get a linker error saying that CreateFileW could not be found. After searching with depends.exe this does appear to be the case as only CreateFileA is exported.
Is unicode not yet supported in the api? (or is this an unintentional mistake due to the use of macros in the windows header files?)

system headers requirement

2009-07-13T05:41:35-05:00

The header cdbdb.h has dependencies on system header files for _MAX_PATH (stdlib.h) and NULL (stddef.h).
Ideally it should either include the dependencies explicitly or remove them.

CDB Path Problems

2009-07-13T05:12:37-05:00

I have experienced some problems when trying to open CDB db’s in different places. So far I have only managed to get the API to open a CDB if it is on my local system and does not end with \‘s, e.g.
c:\myCDB works
c:\myCDB\ does not work

Also I cannot get network CDB db’s to work, e.g.
\server\myCDB does not work
\server\myCDB\ does not work
mapped to T:
T: does not work
T:\ does not work

The only network case I have managed to get to work is if I map a network drive to the directory below the network CDB dataset, e.g.
\server\dbsmyCDB
T: -> \server\dbs
and then try to connect to
T:\myCDB
the API then succeeds (although I have only tested this by mapping a drive to a locally created share).

API Testing

2009-06-16T04:45:08-05:00

I have re-implemented a CDB tile viewer using the CDB API and have a few things to mention. The viewer just generates a regular mesh from elevation and then applies the imagery to it, no 3d models or other layers.

1. It took me about 3-4 hours to adapt the test app to using the CDB API

2. There is no simple search mechanism in the CDB API so I left my own. CDB API only allows opening a specific file. It might be useful to be able to check if a sub-tree was available and even enumerate members, e.g. what layers are available for tile LAT,LONG. i.e. the sample project explicitly specifies the lat long, what if this was not known?

3. I don;‘t think that the error reporting is sufficient, i.e. if the JP2K dll is not present then any files reliant on it seem to just report a ‘not found’ error.

4. Running the application either requires adding the CDB dll paths to my project environment settings or copying the dlls into my bin directory. As both debug and release CDB dlls have the same name then I can’t do this (although I realise that many people have seperate debug and release directories). Personally I prefer that debug dll’s are appended with a *_d.dll to explicitly differentiate them.

I think it would be useful to have some sample applications that do something a bit more adventurous with the CDB data than copy it too! Maybe some basic OpenGL viewer or attribute dumper or similar.
Something like a CDB browser that shows the CDB as a tree view and when a file is selected it is displayed in the viewing pane would be useful, and would demonstrate use of each data type quite well in isolation.

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2009-05-08T10:58:24-05:00

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