photogram

photogrammetry pipeline

1. Conversion to DNG format

Convert all files to the widely used DNG raw photo format.

cd photogram/
for file in ./test_data/*.CR3; 
	do dnglab convert $file dng_data/${file%.CR3}.DNG;
done

2. Apply color calibration to photos

The X-rite color palette is supported in darktable.

• https://docs.darktable.org/usermanual/3.6/module-reference/processing-modules/color-calibration/#supported-color-checker-targets This states "If the lighting conditions are peculiar and far from standard illuminants, the color checker shot will be only usable as an ad-hoc profile for pictures taken in the same lighting conditions."

• https://pixls.us/articles/profiling-a-camera-with-darktable-chart/

darktable-cli ...

3. Cluster and organize photos

3.1 by angle-rotation

• https://towardsdatascience.com/how-to-cluster-images-based-on-visual-similarity-cd6e7209fe34
• https://keras.io/examples/vision/semantic_image_clustering/

# python script using opencv
opencv?

3.2 by time intervals

Use ExifTool to extract the timestamp of photos, indentify to intervals by 1) setting manual threshold, or 2) fitting them into gmm distribution.

SOFTWARE

• [DNGLAB] A tool for converting between raw formats, specifically here for CR3 -> DNG, since very few tools support CR3. Tested and working. Install from .deb or source.

• EXIFTOOL Command line perl program for editing meta data (EXIF) on various file formats. A dependency of ART. Can be installed within conda.

• ART This is a fork of RawTherapee, a windows-only tool for converting between different raw file formats. It is the only Linux software I have found that can load the proprietary Canon raw format CR3. Available install from APT.

• [DARKTABLE] A lightroom-like raw photo viewer and editor. Can be used to apply color corrections. Has a command line utility darktable-cli that may be able to implement batch processing. Available install from APT.

DNGLAB -> DARKTABLE -> 

0. Collect a set of images from the same sample.
1. Color correct and convert image to JPG
   • X-RITE software (free but NOT LINUX)
   • CRAW format (.CR3) is not supported by darktable.
2. Identify sets of images from the same angle.
   • Image clustering analysis
3. Focus stacking of images from the same angle.
   • Helicon Focus
   • photoshop
   • enfuse (free Linux)
4. Background removal
   • Automate... maybe gimp or OpenCV
5. Build mesh model
   • AGISOFT