[gdal-dev] [EXTERNAL] Re: Converting OBJ to Geojson files with ogr2ogr

[Clay, Bruce]

Take a look at CityXml / CityGml and CityJson.  There is partial support at least in GDAL based on web searches.  Also some support for QGIS through a plugin


Bruce


________________________________
From: gdal-dev <gdal-dev-bounces at lists.osgeo.org> on behalf of Paul Harwood <runette at gmail.com>
Sent: Wednesday, December 2, 2020 5:31 AM
To: Andrew C Aitchison
Cc: gdal-dev at lists.osgeo.org
Subject: [EXTERNAL] Re: [gdal-dev] Converting OBJ to Geojson files with ogr2ogr

.OBJ is a simple object mesh  (or to put it in more traditional terms: TIN) - it has shape but no data values and is not geolocated.

I don't think there is any driver for OGR that will read .OBJ.

You are going to problems with geolocation if you write your own. Geojson requires that the geometries are geolocated - and in the current version that they are in epsg:4326. That is not totally impossible - people have been using .dxf files for gis data for decades and that format is also not in theory geolocated. It is not a trivial problem though.

I guess I would ask the usual question .. why?

- what are you actually trying to achieve and why a GIS format like GeoJSON?

- If you have to use GeoJSON - I am guessing you are transferring some data to something that reads GeoJSON only? In that case - can your source produce .dxf? OGR can read .dxf.

- If you only have the source in .OBJ - what other formats can the destination read? Although, if you only have the source in .obj, I very much doubt any of the GIS tools like GDAL are going to be able to help you. It just is not a format used in GIS.

It is a problem we solved in the ViRGiS projec<https://usg02.safelinks.protection.office365.us/?url=http%3A%2F%2Fwww.virgis.org%2F&data=04%7C01%7C%7C0da679eff03c4694022308d896ad7f40%7C3430c5de5e6f4f9d9d9690e985038b58%7C0%7C0%7C637425019296346911%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=P2rkx2BIsKJ0GPY3EdGesGO%2B9Az%2FTB5s0f9YMRkH%2FH0%3D&reserved=0>t - since .obj is used a lot in VR. There we used an existing library to read the .obj files - but that is in C# and I doubt that would help you.

On Tue, 1 Dec 2020 at 20:15, Andrew C Aitchison <andrew at aitchison.me.uk<mailto:andrew at aitchison.me.uk>> wrote:
On Tue, 1 Dec 2020, Brandon Biggs wrote:

> Hello,
> I am wondering how to convert an obj file to a geojson file? I am using ogr2ogr with the command:
> Ogr2ogr -f geojson output.geojson input.obj
> But get the error that ogr2ogr does not have an OBJ driver. I looked on:
> the vector drivers page<https://gdal.org/drivers/vector/index.html<https://usg02.safelinks.protection.office365.us/?url=https%3A%2F%2Fgdal.org%2Fdrivers%2Fvector%2Findex.html&data=04%7C01%7C%7C0da679eff03c4694022308d896ad7f40%7C3430c5de5e6f4f9d9d9690e985038b58%7C0%7C0%7C637425019296346911%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=YlMoWYX%2FArELUfRlhGmaqSd8H%2BQeyhJKoWz2FZSQoNM%3D&reserved=0>>
> but am unable to find a simple obj converter. I am wondering if there is such a thing? I am probably going to write my own that does what I want, because OBJ is so simple, I was just wondering if GDAL could already do it.

I've never heard of OBJ, but that doesn't mean much.

If you only want a read-only ogr driver you might want to look at
        https://gdal.org/tutorials/vector_python_driver.html<https://usg02.safelinks.protection.office365.us/?url=https%3A%2F%2Fgdal.org%2Ftutorials%2Fvector_python_driver.html&data=04%7C01%7C%7C0da679eff03c4694022308d896ad7f40%7C3430c5de5e6f4f9d9d9690e985038b58%7C0%7C0%7C637425019296356903%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=ulnrpqd06IeuubvWwEkSSFhsPUWFw9rsfdYfGWf0zis%3D&reserved=0>
if you would find a quick-n-dirty python quicker to write than C++.

--
Andrew C. Aitchison                                     Kendal, UK
                        andrew at aitchison.me.uk<mailto:andrew at aitchison.me.uk>
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