TABLE 1. Advantages and disadvantages of STL, PLY, DXF, 3DS, VRML/X3D and PDF/U3D file formats as candidate virtual palaeontology dissemination formats.
|STL & PLY||Simple file format, widely used and understood by almost all software. Two subtypes – human readable (ASCII) format, computer readable (binary) format.||No capacity for multiple objects; no capacity for storage of metadata; ASCII STL files are very large; binary files smaller but lack compression facilities. STL files cannot store vertex colour information. PLY files can include non-standard attributes.|
|DXF||Simple file format, widely used and understood by most software. Human readable. Multiple named objects supported.||Files typically very large (larger than STL); very limited facilities to store approriate metadata (limited to names essentially - no facility to correctly represent colour of objects for instance).|
|3DS||Flexible format, compact, allows for some accompanying metadata.||Limit of 65536 triangles per mesh; lacks facilities for abitrary metadata tagging of objects; not human readable.|
|VRML/X3D||Widely used format, though not as extensively so as STL and DXF; VRML (older iteration) human readable, some metadata facilities; X3D provides more compact binary files at expense of human readability.||VRML files in particular typically very large (larger than DXF); viewing software relatively low performance (and X3D software scarce), do not scale well to large triangle-count models; lack facilities for abitrary metadata tagging of objects.|
|PDF/U3D||3D PDFs (incorporating U3D) data can be viewed in free Adobe Reader software, already deployed to the bulk of computers; good metadata facilities; relatively small file sizes||Limited range of viewing software (limited essentially to Adobe Reader) that lacks key facilities (e.g. stereo-viewing), does not support export of data, and is unproven for large triangle count models; lack of free export tools to generate files; lack of transparency and human readability in file format.|