[pdal] How to invoke my custom writer?

[Andrew Bell]

You need to build your writer (a plugin) into a shared object that can be
loaded by the plugin manager.  It needs to be called
libpdal_plugin_writer_PdalVectorMapWriter.<your shared library extension>.
The shared library needs to be located somewhere that the plugin manager
can find it.  By default, PDAL will look in the following directories for
plugins:

".", "./lib", "../lib", "./bin", "../bin"

If you're using cmake, you can use the PDAL build to generate the shared
library for you.  Here's an example plugin:

https://github.com/gadomski/cpd.git

Note that you don't have to do ANY of this if you're not using the
pipeline/plugin manager to run your writer from a JSON pipeline.  If you're
executing code programmatically, you can simply add your writer to the end
of a pipeline and call prepare() and execute() on the pipeline that you've
created in code.


On Tue, Jul 11, 2017 at 10:59 AM, Paul Schrum <paul.schrum at gmail.com> wrote:

> Thank you Andrew.
>
> In the cpp file containing the class, I have the following lines:
>
>   static PluginInfo const s_info = PluginInfo(
>     "writers.PdalVectorMapWriter",
>     "Custom Writer to write a GRASS Vector Map",
>     "http://no/documentation/yet" );
>
>   CREATE_SHARED_PLUGIN(1, 0, PdalVectorMapWriter, Writer, s_info);
>
> So would the only other thing I need to do be to tell pdal where to find
> the class?  I don't have to instantiate the class and pass it the instance?
>
> The class lives in my GRASS executable, v.in.pdal.  How do I tell pdal to
> append PDAL_DRIVER_PATH with v.in.pdal's path, and is that sufficient?
>
> I see in https://github.com/PDAL/PDAL/tree/master/plugins that these are
> built using CMake.  But GRASS uses make, so I don't know how to make these
> work together.  Is it not possible for me simply to pass an instance of my
> class to some kind of pdal->registerPlugIn() function or something similar
> which happens at runtime?
>
> - Paul
>
>
> On Mon, Jul 10, 2017 at 7:56 PM, Andrew Bell <andrew.bell.ia at gmail.com>
> wrote:
>
>> You need to build your writer as a shared plugin and make sure that the
>> dll/so that you create is in a folder where the plugin manager will look
>> for it (or set PDAL_DRIVER_PATH).  Take a look at one of the existing
>> plugins in the "plutgins" subdirectory of pdal.  Let me know if you need
>> more help.
>>
>> On Mon, Jul 10, 2017 at 5:11 PM, Paul Schrum <paul.schrum at gmail.com>
>> wrote:
>>
>>> I am developing a custom PDAL writer for my GSoC project. (Link
>>> <https://trac.osgeo.org/grass/wiki/GSoC/2017/IntegrationOfPDALintoGRASSGIS>)
>>> Source Code is on github <https://github.com/PaulSchrum/v_in_pdal>.
>>> The module compiles, but it is an intermediate state since I am in the
>>> process of developing it.
>>>
>>> I have the custom writer, PdalVectorMapWriter,  inheriting from writer
>>> and it compiles okay.  Currently all functions just print out their own
>>> name and return.
>>>
>>> In main.cpp I create the pipeline json string and create a
>>> PipelineExecutor with it.  I then call pipeline-> validate.  This throws an
>>> exception stating
>>>
>>> terminate called after throwing an instance of 'pdal::pdal_error'
>>>   what():  Couldn't create writer stage of type
>>> 'writers.PdalVectorMapWriter'.
>>>
>>> So I am thinking that I need somehow to inform Pdal about an instance of
>>> the class.  But as I go over the Pdal documentation, I do not see how to do
>>> that.  Can someone help me understand what I need to do?
>>>
>>> - Paul
>>>
>>> Here is a key code snippet:
>>> 81    std::string pipeline_json =
>>> 82            pipelineJson::basicVectorMapReaderWriter(inFile,outFile);
>>> 83
>>> 84    cout << pipeline_json << endl;  //diagnostic only
>>> 85    cout << endl;
>>> 86    G_important_message(_("Running the pipeline ..."));
>>> 87    auto pipeline = new pdal::PipelineExecutor(pipeline_json);
>>> 88
>>> 87    cout << "is valid?  " << pipeline->validate() << endl;
>>>
>>> Line 87 throws the exception.
>>>
>>>
>>> Here is the json string being passed to the PipelineExecutor constructor:
>>>
>>> { "pipeline":[
>>>    "/home/user/Desktop/ALL/SourceModules/cpp/grass7_trunk/vecto
>>> r/v.in.pdal/testFiles/100-points.las",
>>> {
>>>    "type":"writers.PdalVectorMapWriter",
>>>    "filename":"100-points"
>>> }
>>>  ]
>>> }
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> pdal mailing list
>>> pdal at lists.osgeo.org
>>> https://lists.osgeo.org/mailman/listinfo/pdal
>>>
>>
>>
>>
>> --
>> Andrew Bell
>> andrew.bell.ia at gmail.com
>>
>
>


-- 
Andrew Bell
andrew.bell.ia at gmail.com
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