panoscripts

Scripts and notes for making panoramas from multiple images

Requirements:

• bash
• hugin (for tile_panorama.sh)
• vips (for tile_panorama.sh and make_presentation.sh)
• GraphicsMagic (for tile_panorama.sh)
• wget (for make_presentation.sh)

Scripts

reset_exposure.sh

Resets exposure and tint for all images in a panorama.

Hugin can automatically correct exposure and tint for images. This is done as part of the default processing, when using the simple interface. If the images has been taken with variable exposure, this might be a fine idea, but sometimes the result leaves very bright, very dark or strangely tinted images.

See also http://hugin.sourceforge.net/docs/manual/Vig_optimize.html

tile_panorama.sh

Slices a panorama into smaller tiles at PTO-level, renders the individual tiles using hugin_executor and uses vips for merging the resulting tiles into a single image.

Hugin uses enblend for stitching panoramas (creating the final large image). Unfortunately enblend has a hard time scaling up to hundreds of images and gigapixels size on a 32GB machine.

Creating multiple smaller tiles is lighter than creating a single large image and the tool vips is capable of merging these tiles into a single image with ease.

The challenge here is to avoid visible seams between the tiles. This is done by having an intermediate overlap between tiles. It has not been researched how large that overlap should be and it probably depends on the image. The driving problem that leas to this script was a 160000x12924 pixel image and when cut into tiles of 16284x16384 pixels, an overlap of 8000 was needed to make the seams invisible.

add_masks.sh

Given a grid of images as source for the panorama, this scripts adds exclusion masks to the bottom or to the right of every image, except for those at the lowest row or rightmost column respectively.

enblend 4.0 sometimes complain about excessive overlap detected without it being possible to remove any images (without leaving holes). "Removing" part of the overlap by adding exclusion masks solves this problem at the cost of less pixels to blend.

The smaller amount of pixels might be a problem if the different has different exposures.

make_presentation.sh

Given a finished panorama bitmap (or any bitmap), this script cuts it into DeepZoom tiles using vips and creates a web page where the panorama is displayed using OpenSeadragon.

validate_control_points.sh

Given a grid of images as source for the panorama, this scripts validates the control points by checking that

• Images are connected to their neighbours
• Images are not connected to other images that they should not be connected to
• Horizontal and vertical lines does not differ from the mean by more than X percent

Note: The check for horizontal and vertical lines has not been implemented yet

find_grid_control_points.sh

Given a grid of images as source for the panorama, this scripts creates a PTO-project, adjusts the image positions to overlap where the grid dictates there should be overlap and calls cpfind with the prealigned option which only detects control points for overlapping images.

This should be markedly faster and with a lot fewer false positives than the default no-assumptions control point search.

This script is an adaption from a rex-script by "mfc".

Notes

Generate a preview image of width 20000 from a large image using vips:

vips thumbnail in.tif 'out.jpg[Q=80,strip]' 20000