Photogrammetry
- Doug Boyer
Workflows for creating photogrammetry models are quite diverse depending on camera's used, presence of targets or scalebars, whether camera positions and angles are "known" and physical or inferred from the photo collection itself. There are an increasing variety of algorithms and software used for extracting models. The basic assumptiion of MorphoSource for photogrammetry deposits is that the "raw" data will be a zipped collection digital photographs, and that any derivative from collection should either (1) contain all the information to create a textured modeled based, (2) be a textured model, or (3) be a derivative from a textured model. An example of different levels of detail in a photogrammetry deposit is shown here.
| Criteria | Raw data | Derivative data 1 | Derivative data 2 | Derivative data 3 | Derivative data 4 | Derivative data 5 |
|---|---|---|---|---|---|---|
| Importance for reproducibility and reuse | workflow dependent* | workflow dependent* | medium* | medium | high | low |
| type | collection of digital photographs | collection of digital photographs cropped to object of interest | collection of digital photographs (cropped/uncropped) with photo-masks | sparse and/or dense point clouds | 3D model with textures | image (screenshot) |
| format(s) | any raster format (lossless preferred) | any raster format (lossless preferred) | any raster format (lossless preferred) | .ply file(s) | (obj+mtl+texture); glb; (gLTF+texture); ply | any open raster |
| zip*** files required/recommended/discouraged** | required | required | required | required if multiple files present | required when using obj+mtl+texture; note that neither ply or stl are compatible with textures | disallowed |
| critical metadata for accurate reuse | information on targets, distances, and units if available | none if raw data are provided with critical metadata | none if raw data are provided with critical metadata | units of point cloud coordinates (if other than millimeters) | units of mesh coordinates (if other than millimeters) | none |
| recommended attachments | list of camera positions/orientations if known/physical as .txt or .pdf | list of camera positions/orientations if known/physical as .txt or .pdf | list of camera positions/orientations if known/physical as .txt or .pdf | list of camera positions/orientations if computed as .txt or .pdf | (1) list of camera positions/orientations if computed as .txt or .pdf; (2) photogrammetry software model reports (e.g. as generated by metashape as .pdf | na |
| Thumbnail**** | sample image from photograph collection | sample image from photograph collection | sample image from photograph collection | screen shot of point cloud(s) | screenshot of segmented mesh with texture | na |
| Preview setting | Select "use 2D thumbnail" | Select "use 2D thumbnail" | Select "use 2D thumbnail" | Select "use 2D thumbnail" | Select "interactive preview" | na |
*One or more of these three data types is critical for data reproduceability and reuse
**"discouraged" means that the system does not prevent you from uploading a zip for the given derivative type, but mostly likely a member of the MorphoSource support team will eventually contact you and ask you to replace the zip with something else.
***zip files should never be created using OS archiving tools (instead, use freeware: Mac - Keka / PC - 7zip). Zip files should always be saved in .zip format.
****Thumbnails cannot be larger than 50mb in size or the system will reject them and notify you of the rejection.