# SCM Repository

# View of /branches/vis15/src/tests/examples/vimg/README.md

Parent Directory | Revision Log

Revision

File size: 2931 byte(s)

**4178**- (**download**) (**annotate**)*Fri Jul 8 18:47:11 2016 UTC*(3 years, 1 month ago) by*jhr*File size: 2931 byte(s)

updating examples in merge to latest put from github

## vimg.diderot: 2D image sampler/viewer This program needs a dataset to render, and a colormap, for example: ln -s ../data/sscand.nrrd img.nrrd ln -s ../cmap/spiral.nrrd cmap.nrrd Then compile this program; assuming the directions at https://github.com/Diderot-Language/examples you can: ../../vis12/bin/diderotc --exec vimg.diderot If the needed `img.nrrd` file is missing, the error message looks something like: uncaught exception Fail [Fail: Nrrd file "img.nrrd" does not exist] raised at common/phase-timer.sml:78.50-78.52 raised at common/phase-timer.sml:78.50-78.52 raised at nrrd/nrrd-info.sml:146.15-146.74 in which case you should run the `ln -s` command above, or link `img.nrrd` to some other 2D scalar nrrd file to view. The same applies to the need for `cmap.nrrd` to link to a colormap. The `-which` option will determine which function is sampled; look for `(0 == which)` below to see the start of the function definitions. Assuming the symbolic links given above (of `img.nrrd` and `cmap.nrrd` to `../data/sscand.nrrd` and `../cmap/spiral.nrrd` respectively), some examples usages are: * Grayscale image of reconstructed field: `./vimg -cent 290 414 -fov 45 -which 0` * Grayscale image of gradient magnitude: `./vimg -cent 290 414 -fov 45 -which 1` * Color image of gradient vector (blue is always zero): `./vimg -cent 290 414 -fov 45 -which 2` * Colormapped field, with naive pseudo-isocontour: `./vimg -cent 290 414 -fov 45 -which 3 -cmin -500 -cmax 1900 -iso 1210 -th 20` * Colormapped field, with smarter pseudo-isocontour: `./vimg -cent 290 414 -fov 45 -which 4 -cmin -500 -cmax 1900 -iso 1210 -th 0.2` * Colormapped field, with ridge lines: `./vimg -cent 290 414 -fov 45 -which 5 -cmin -500 -cmax 1900 -th 0.2 -sthr 2` * Colormapped field, with valley lines: `./vimg -cent 290 414 -fov 45 -which 6 -cmin -500 -cmax 1900 -th 0.2 -sthr 2` * Colormapped field, with blue maxima: `./vimg -cent 290 414 -fov 45 -which 7 -cmin -500 -cmax 1900 -th 0.25 -sthr 25 -fcol 0 0 0.8` * Colormapped field, with green saddle points: `./vimg -cent 290 414 -fov 45 -which 8 -cmin -500 -cmax 1900 -th 0.25 -fcol 0 1 0` * Colormapped field, with cyan minima: `./vimg -cent 290 414 -fov 45 -which 9 -cmin -500 -cmax 1900 -th 0.25 -sthr 25 -fcol 0 1 1` Each command can be followed by `unu quantize -b 8 -i rgb.nrrd -o rgb.png` to create an 8-bit image version of the output. The `-which 3` and `-which 4` commands show an important comparison, demonstrating how knowing the gradient permits drawing of equal-thickness isocontours (according to the first-order Taylor expansion). Viewing `../data/sscand.nrrd` with the parameters above gives a roughly 100km view of the area around Geilo, Norway, site of the [Winter School](http://www.sintef.no/projectweb/geilowinterschool/2016-scientific-visualization/) for which this program was originally created.

root@smlnj-gforge.cs.uchicago.edu | ViewVC Help |

Powered by ViewVC 1.0.0 |