meshmap/warp fisheye

Discussions
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1

for the spec of the meshmap file it indicates the first value can be 1 or 2. The value one is panorama, two is fisheye imagery.

In the vuo warp fisheye module, does it process #1?
Does the first value alter the xy-uv processing?
Is the first value actually used for something besides metadata tag?

2

Is there a way to put a comment line in the file?

for example, ‘#’ in column 1?  

3

for the spec of the meshmap file it indicates the first value can be 1 or 2. The value one is panorama, two is fisheye imagery. In the vuo warp fisheye module, does it process #1? Does the first value alter the xy-uv processing? Is the first value actually used for something besides metadata tag?

Paul Bourke wrote the spec for this format: http://paulbourke.net/dataformats/meshwarp/.
As far as we know it’s just metadata; in Vuo, at least, its value doesn’t affect the rendered output.

Is there a way to put a comment line in the file? for example, ‘#’ in column 1?

The spec doesn’t include a way to add comments.

4

The response from Jean Marie above is correct, the first number indicates the type of image projection the mesh is intended for. The way the warping is performed is not dependent on that value, it was originally added as a way of indicating other things, in particular

  • For some image projections wrapping may be applicable while for others it isn’t, eg: circular panoramas vs fisheye.
  • It can be used to indicate what forms of navigation are appropriate, for example “roll” may be applicable for a fisheye but not a perspective image.

And yes, I forgot to add the ability to insert comments. The format was dreamt up as something I imagined only I would use for my own projects/software. Then it “escaped” at which point I couldn’t add features without breaking code others had written … including the implementation in QuartzComposer. If I had thought ahead a bit more I would have included comments. Sorry about that.

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5

regarding inserting format ID comments within meshmap, this can be solved using HDF5’s userblock.

The userblock is a fixed-length block of data located at the beginning of the file and is ignored
by the HDF5 library. This block is specifically set aside for any data or information that
developers determine to be useful to their applications but that will not be used by the HDF5
library. The size of the userblock is defined in bytes and may be set to any power of two with a
minimum size of 512 bytes. In other words, userblocks might be 512, 1024, or 2048 bytes in
size.

The meshfile format could be extended by appending HDF5 to the meshfile. That is, the meshfile becomes a HDF5 userblock, and comments or other new forms of data could be attached within the HDF5 data structures without altering the meshfile data. Readers ignorant of HDF5 would start reading the meshfile data at the first byte of the file. Readers cognizant of HDF5 could extract additional information.