3D Conversion

This repository contains some code used for converting 3d object files from OBJ format to glTF files. The reason for doing this was that sul-embed had been using virtex3d for viewing the OBJ files, and it is no longer being maintained. model-viewer was selected as a replacement, but it only works with glTF files. So we need to update SDR 3D objects to include a glb file, which is the compressed binary version of glTF files.

Argo was used to create a report of 3D objects that have been accessioned, and then save the druids as text file druids.txt. This file was used to export the objects using SDRGET, and the data was transfered to the bags directory with rsync. Additionally an Argo Batch Job was used to export the structural metadata for the same set of 3D items, which was saved as structural.csv.

Once bags was transferred and the bags were validated the following commands were run:

$ yarn install
$ ./convert.rb

This installs the [obj2gltf] conversion program and then uses it create a set of new files in the output directory.

Conversion Errors

When running the conversion in November 2023 the following errors were encountered:

Missing obj files

• hc941fm6529 lacked an OBJ file, which wasn't fixable.

Missing texture files

The obj file often references a material file (.mtl) which references texture files (.jpg). In some cases the referenced texture files were just missing. The missing texture files didn't prevent a GLB file from being created, and didn't result in a degradation in viewing since it was a problem with the OBJ file as well.

• ng589kj1631 was lacking: white_limestone2.jpg, White_Plaster_Transparent.jpg, white_mudplaster.jpg, White_Plaster_Transparent_Transparent.jpg, pink_granite2.jpg, white_limeston_block.jpg, White_Plaster_Transparent_Transparent1.jpg, white_mudplaster1.jpg, mudplaster1.jpg
• rj811bj9781 was lacking Emery1961_3035.jpg

Misnamed MTL files

There were also some .obj files that referenced material files incorrectly (.mtl):

• Could not read material file at bags/cb462jn0451/data/content/Huynefer&Nebnefer_ST217.mtl
• Could not read material file at bags/fh129xw6834/data/content/Pay&Raia.mtl
• Could not read material file at bags/fp375qc0402/data/content/Nebnefer&Mahu_ST218.mtl
• Could not read material file at bags/sz524fd9637/data/content/Ra'ia.mtl
• Could not read material file at bags/tx237xp2328/data/content/Rest House.mtl
• Could not read material file at bags/vg134yk1706/data/content/Maya&Meryt.mtl

Since there didn't seem to be a reliable pattern for these errors the .obj files, and the files were present, the .obj files were manually updated to point to the correct .mtl file. These

Accessioning

Preassembly was used to add the new 3D GLTF files to the SDR. The existing structural.csv metadata was updated using a Python program (update_structural.py) which uses Pandas to selectively update and add to the table. This modified table is written to output/file_manifest.csv and a output/manifest.csv was used to map the druids to folder locations, for use with Preassembly. The entire output directory was transferred to Preassembly using Globus. The resulting discovery report can be found at https://sul-preassembly-prod.stanford.edu/job_runs/11863.