[CE U15] BigTIFF support

Oto said:

Is BigTIFF format supported or not?

Wikipedia tells us: The TIFF file formats use 32-bit offsets, which limits file size to around 4 GiB. Some implementations even use a signed 32-bit offset, running into issues around 2 GiB. BigTIFF is a TIFF variant file format which uses 64-bit offsets and supports much larger files (up to 18 exabytes in size).[30] The BigTIFF file format specification was implemented in 2007 in development releases of LibTIFF version 4.0, which was finally released as stable in December 2011. Support for BigTIFF file formats by applications is limited.

MicroStation help mentions Internet TIFF64.  Is that BigTIFF?

iTIFF64 is Bentley implementation of BigTIFF before big TIFF was finalized so this could be a problem that it doesn't recognize TIFF correctly and tries to open it as iTIFF. This file seems to be actually GeoTIFF-BigTIFF in LZW compression but iTIFF doesn't support LZW.

Oto said:

iTIFF64 is Bentley implementation of BigTIFF

I understand iTiff64 as evolution of original HMR specific iTIFF format, whereas BigTIFF is evolution of TIFF format itself.

Both formats try to solve the same problem (which is 32bit address space), but were probably invented and implemented independently. But because they have to follow common TIFF format concepts, the implementations will be probably similar.

Anyway: Even when I have not met BigTIFF format in any project yet, it sounds like good idea to support it in MicroStation (even e.g. to be converted to iTiff64 only, so data can be displayed).

Regards,

  Jan

Seems there was some influence from bigtiff specification - https://communities.bentley.com/products/geospatial/desktop/f/bentley-map-forum/63061/what-is-limitation-of-itiff-and-itiff64-file-format/162544

Perhaps Mathieu St-pierre could comment?