[gdal-dev] GeoPDF Writing support using Create()?

[Robert Zermeno]

Even,

>But as CreateCopy() is already implemented, you can for example create a
>in-memory raster (see the MEM driver) and CreateCopy() it into a geospatial PDF.


Awesome!  I did not know of the MEM driver.  Looking at the specs from http://www.gdal.org/frmt_mem.html  it kind of reminds me of
GDAL virtual format (.vrt) as I think it uses the MEM driver under the hood.

So, essentially you are telling me I can create a MEM object and store my image band information to the recently created GDALDatasetH object (I use the C API) and
to set PDF metadata via GDALSetMetadata().  Would that be the direction I could go to use CreateCopy() for a valid Geospatial PDF file?

I do have a few questions on PDF creation fields:

1. If a neatline is not provided, what gets populated in the neatline?

2. For EXTRA_CONTENT_STREAM and EXTRA_IMAGES, are we limited to one entry?  Is it each time we call GDALSetMetadata() is will append another
entry request?

Correct me if I am wrong, but EXTRA_CONTENT_STREAM is associated by EXTRA_IMAGES where EXTRA_IMAGES tells the PDF file where on the page to
display the EXTRA_CONTENT_STREAM data?
My concern is how to add multiple entries of EXTRA_CONTENT_STREAM?   I know the content stream is described by its information and EXTRA_IMAGES and EXTRA_CONTENT_LAYER_NAME.


I hope you understand my thoughts.  


Thanks for the response,

Robert




________________________________
 From: Even Rouault <even.rouault at mines-paris.org>
To: Robert Zermeno <refriguy68 at yahoo.com> 
Cc: "gdal-dev at lists.osgeo.org" <gdal-dev at lists.osgeo.org> 
Sent: Wednesday, November 21, 2012 4:11 AM
Subject: Re: [gdal-dev] GeoPDF Writing support using Create()?
 
Selon Robert Zermeno <refriguy68 at yahoo.com>:

> GDAL Community (Especially Even Rouault),
>
> It has been around 1 1/2 years the last time I had used GDAL and noticed GDAL
> now has capabilities of generating Geospatial PDF files from existing
> GDALDataset objects.  How far in the future do you see GDAL having
> capabilities of using Create() to generate your own Geospaital PDF?
>
> I would like to have the freedom of providing GDAL all the required, and
> optional, information needed to generate a Geospatial PDF file from a given
> image buffer my application possesses.  I am not sure if any other GDAL
> community members concur with my desire.
>
> What would be the effort level to supply Create() for Geospatial PDF files?

Implementing Create(), with the capability of random writing (for example like
being needed by gdalwarp or nearblack), is not doable due to the nature of PDF.
But as CreateCopy() is already implemented, you can for example create a
in-memory raster (see the MEM driver) and CreateCopy() it into a geospatial PDF.

>
> Robert
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