<html><head><style type="text/css">.style1 {font-family: "Times New Roman";}</style></head><body><div dir="ltr">Hello GDAL community,<div><br></div><div>The product that I work on uses the CPP GDAL library for a number of routines. Occasionally, this requires supplementary files -- Currently, we supply <a href="https://github.com/OSGeo/PROJ-data/releases/tag/1.20.0">proj-data 1.20</a> -- which we download when we detect that the dataset is needed. Here's the problem, often GDALRegisterAll() is called before the proj-data 1.20 files are downloaded. From my testing, it appears that if the proj-data 1.20 files are not available when GDALRegisterAll() is called, GDAL will not use them regardless of whether or not these files are available later.</div><div><br></div><div>Now, what I think might be a good solution is appropriately updating GDAL's state after proj-data is downloaded s.t. it is able to detect the proj-data files. But, I'm not sure how to do this. Calling the following seems to produce correct results:</div><div><br></div><div>GDALDestroy()</div><div>GDALAllRegister()</div><div><br></div><div>However, the documentation says the following:</div><div><br></div><div>///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////FROM DOCUMENTATION///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////</div><div>Finalize GDAL/OGR library.<br><br>This function calls GDALDestroyDriverManager() and OGRCleanupAll() and finalize Thread Local Storage variables.<br><br>Prior to GDAL 2.4.0, this function should normally be explicitly called by application code if GDAL is dynamically linked (but that does not hurt), since it was automatically called through the unregistration mechanisms of dynamic library loading.<br><br>Since GDAL 2.4.0, this function may be called by application code, since it is no longer called automatically, on non-MSVC builds, due to ordering problems with respect to automatic destruction of global C++ objects.<br><br><b>Note: no GDAL/OGR code should be called after this call!</b></div><div>///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////FROM DOCUMENTATION///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////</div><div><br></div><div>So, this doesn't seem like the correct way to address this problem. How should I go about updating GDAL's state s.t. it will detect and read the downloaded supplementary proj-data files? Or, is there something more I should be doing before GDALAllRegister() is called?</div><div><br></div><div>GDAL Version: GDAL 3.10.3, released 2025/04/01<br>Proj Version: 9.6.0</div><div><br></div><div>P.S. To get out in front of what I expect to be the first question, yes I am setting the PROJ_LIB environmental variable at runtime to the correct folder. Further, I have tried creating an empty proj-data folder available to GDAL when GDALRegisterAll() is called. This did not change GDAL's behavior. Here is the code I use for setting PROJ_LIB:</div><div><br></div><div>SetEnvironmentVariable("PROJ_LIB", "c:/path/to/proj-data/folder");<br>_putenv_s("PROJ_LIB", "c:/path/to/proj-data/folder"); // (See: GETENV_NOTE)</div><div><br></div><div>P.P.S Here is the GETENV_NOTE:</div><div>// GETENV_NOTE:</div><div>// _putenv_s() is used to ensure compatibility with getenv(). getenv() operates on environment variables loaded into the _environ global variable (loaded at "process startup.")<br>// SetEnvironmentVariable() affects the environment variables set for this process but does not change _environ. _putenv_s() updates _environ and ensures compatibility w/<br>// genenv().</div><div><br></div><div>P.P.P.S I do know that there is a more current proj-data dataset available. We may update to this dataset in the future. But unless that will fix the current issue, I'd rather not do that now.</div><div><br clear="all"></div><div><br></div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">David Klaus<div>Carlson Software</div></div></div></div>
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