# Hugin Preferences

From PanoTools.org Wiki

# General

## Resource usage

To speed things up Hugin keeps a copy in memory of as many input photos as possible. With very large projects, this would use all your system memory, so set Image cache memory to a value below your available free RAM. The default of 256MB should be ok for a system with 512MB of RAM, however this is very conservative, for large projects you will want to set this to a high proportion of your available system memory.

The Preview window is multi-threaded so can use more than one CPU/core if required. Set Number of CPUs to how many CPUs you wish to use.

## User interface

Changing the language of the user interface can be useful e.g. if you want to test your new translation.

Usually, Hugin will use the current locale to determine the language of buttons, menus etc... Set the Language if you need to switch languages temporarily or if you are using a platform such as Windows95 that doesn't support localised software. Hugin won't change language immediately, you will need to stop and restart it.

The "language" option in the Hugin Preferences doesn't work for the Mac version. On Mac OS X the system's country settings will be used instead: change the language setting there (i.e. drag the preferred language to the top of the list), and Hugin will reflect that when you restart the program. An alternative but more time consuming way to set another language than the current system language is to quit Hugin, reveal it's icon in the Finder, click on it and open the Information window (Cmd.-I). After deselecting all unwanted language options you can start Hugin in your preferred language.

If the option Copy log messages to clipboard is activated, all log messages (from the control point detector or the assistant) are copied at the end to the clipboard.

# File names

## File options

Some Hugin actions generate large temporary files, change the Temporary dir to specify an alternative location for writing these files. One reason for setting this independently to the operating system default would be to use a RAM disk to speed up stitching.

Note that intermediate stitching files are created in the output folder and not in this Temporary dir.

## Default file names

Here you can construct a default file name for saving the project and for the output prefix. You can always change the proposal when saving. Several place holders can be used to build the file names.

# Assistant

The Assistant tab automates the entire panorama creation process, these settings allow you to customise the assistant.

## Image loading

Select Automatically align images after loading to run the second Align... step immediately after loading the images.

## Automatic control point checking after detecting control points

Select Remove cloud-like control points (Celeste) to run celeste after detecting control points. Celeste will remove Control points set to clouds, this is useful because clouds will move several pixels between shots and are therefore bad scene objects to use for alignment.

Select Remove outlying control points by statistical method to run cpclean, this will try to remove control points with positions that are not credible under pairwise optimisation.

## Auto align

Auto align uses the default control point detector to generate control points between pairs of images, set Number of Ctrl Points per overlap to control the number of control points. Note that although most pictures can be stitched with just three or four control points, automatically generated points tend not to be very evenly distributed, so this number should be set to ten or more.

Note: Hugins cpfind does not support this parameters. So in default settings this parameter is ignored.

The size of the output Panorama Image Size is usually set in the Stitcher tab where it is also possible to Calculate Optimal Size based on the sizes of the input images. The Auto align process does something similar, though here you can set a smaller output as a percentage. Generally setting a percentage of 70% leads to no great loss of quality due to the way a camera CCD samples data.

# Control Points Editor

## HDR and 16bit display

Hugin supports both HDR and 16bit imaging. These image formats contain a lot more brightness and colour information than can be displayed on a standard computer monitor, so Hugin only shows a rough representation of these pictures.

16bit data can have linear or corrected gamma. Linear images appear very dark on many monitors, so set the Curve to gamma 2.2.

For HDR data, try setting the Curve to logarithmic.

Changes to the HDR and 16bit display mode require restarting Hugin to take effect.

## Fine-tune

Hugin helps position control points to within a fraction of a pixel distance automatically:

- When auto fine-tune is selected in the Control Points tab while picking control points.
- When clicking Fine-tune in the Control Points tab
- When picking Fine-tune all Points in the Panorama editor window Edit menu.

- Patch width, the size of the square of pixels taken from the left photo to match with the right photo when picking control points, reduce if this is taking a long time on your system.
- Search area width, the percentage area of the right photo that is searched when picking control points, reduce if this is taking a long time on your system.
- Local search area width, the region of the right photo searched when you click Fine-tune in the Hugin Control Points tab or Fine-tune all Points in the Panorama editor window Edit menu.
- Correlation Threshold. For each Fine-tune, Hugin calculates the quality of the control points match, raise this threshold to reject dubious matches.
- Peak Curvature Threshold, Currently unused.

## Rotation search

Enable this if your photos:

- have a very wide angle Field of View or fisheye Projection.
- are tilted up or down, control points near the zenith or nadir may need to have full 360 degree rotation search

# Control Point Detectors

Hugin uses an internal or external tool for automatically creating control points for a set of images either when

- clicking the 2. Align... button in the Hugin Assistant tab or
- clicking the Create control points button in the Photos tab.

Note: If you have upgraded from an older release of Hugin, you will need to Load Defaults to update these preferences.

In the Control Point Detector Programs list box you can choose between several presets such as:

- Hugin's CPFind - This is the internal general purpose control point generator of hugin.
- Hugin's CPFind + Celeste - This is the same as the CPFind setting but it will also remove points in areas of sky using the celeste[*] tool. See Using Celeste with hugin for more details.
- Cpfind (multirow/stacked) - This is the same as the CPFind setting, except that Align image stack is used to match photos in bracketed stacks.
- autopano-sift-C - a C version of autopano-sift, wwhich needs to be installed separately.
- Panomatic (by Anael Orlinski), which needs to be installed separately.
- autopano-sift-c (multirow/stacked) - This is the same as the autopano-sift-C setting, except that Align image stack is used to match photos in bracketed stacks.
- Align image stack - part of Hugin suite. Note that align_image_stack is not a general purpose control point detector, but it is very effective for aligning images within stacks.
- Align image stack FullFrameFisheye - This the same as the Align image stack setting above except with an additional setting suitable for fisheye images.

Parameters for these tools can be customized in the Hugin Parameters for Control Point Detectors dialog which you can access by clicking one of the buttons Edit... or New....

These parameters are also helpful if you want to use a similar command line tool that isn't already listed. Click the New... button to configure a new preset to use in the Assistant or the Photos tabs.

The Set default button will mark the preset selected in this list box to be used automatically in the Assistant tab when clicking the 2. Align... button.

# Stitching

In the final stitching process nona reprojects and distorts images to fit, enblend takes these images as individual TIFF files and merges them using sophisticated seam positioning and blending and/or Exposure fusion[*] into a single finished image file. These processes can be hold together by PTBatcherGUI[*] or hugin_stitch_project. Select here processor should be used:

- PTBatcherGUI[*] can queue several projects and can also work unattended and shutdown the computer at the end (e.g. running over night)
- hugin_stitch_project can only work on one project. It is not recommended to start several processes simultaneously.

Important note: The settings here are the defaults for new projects, change settings for the current project in the Hugin Stitcher tab.

# Programs

Here you can define programs for the different stitching steps and set default options for them.

## Nona

Here you can set the Default interpolator used during stitching. Interpolation is a quality setting, but the default of Poly3 (Bicubic) is good for most purposes. You are unlikely to notice any difference between interpolators other than that Nearest neighbor is fast but very low quality.

You can Create cropped images by default, these Cropped TIFF images will speed up stitching, but some image editors do not process the offsets correctly.

Use GPU for remapping will activate experimental nona code to remap images using the shading language of the Graphics Processing Unit in modern video hardware. However some projections and the translation parameters are not yet supported by this experimental code. In this case Nona will automatically switch back to CPU calculation.

## Enblend

The Use alternative Enblend program option allows you to use other tools with a similar interface such as smartblend[*] or enblend-mask[*].

enblend supports a range of Additional arguments, for example you may want to set:

- -a Pre-assemble non-overlapping images to speed up blending. This is generally useful, but will slow blending in rare cases.
- -l number Number of levels to use (1 to 29), larger numbers result in wider seams. E.g. setting 1 will result in a 2 pixel wide blend, 8 will result in a 256 pixel wide blend and you are extremely unlikely to want a blend level as high as 16.
- -b kilobytes Image cache block size (default=2MiB)
- -c Use CIECAM02 to blend colors. Your input images need to have embedded colour profiles for this to work.
- -m megabytes Use this much memory before going to disk (default=1GiB). Increase if you have a lot of memory on your system.
- --fine-mask Enables detailed mask generation.
- --no-optimize Turn off mask optimization.

Note that setting Additional arguments here will only effect new projects, to change enblend and enfuse settings for the current project use the Hugin Stitcher tab.

## Enfuse

If one of Exposure fusion output options is selected in the Stitcher tab then enfuse will be used to merge bracketed exposures during stitching.

# Misc

## Celeste

Often a project has many control points attached to clouds in the sky, this is usually unwanted as clouds move between photos. celeste will attempt to identify 'sky' control points and delete them.

## Photometric optimizer

The photometric optimizer on the Exposure tab samples the here given number of points and tries to determine with which camera response curve, vignetting and exposure compensation the images need to be stitch to get no changes in colour or luminescence. For difficult projects it can be helpful to increase this number.

# Troubleshooting

Sometimes when updating a hugin installation new features such as the settings for a new control point editor won't appear where expected. The cause might be a conflict with the preferences file of a previous version of hugin. A good idea before pressing the "Reset do defaults" button might be to back up the old preferences file since it is a plain text file that contains your specific settings in a readable format. Saving this file gives you the chance to recreate these individual settings later on. The name and location of the preferences file is this for the following platforms:

- Linux: ".hugin" can be found in your home directory (FIXME)
- Mac OS X: "hugin Preferences" can be found in Macintosh HD/Users/<YourUserAccount>/Library/Preferences/
- Windows: (FIXME)

Quit hugin, rename the preferences file (e.g. add the previous version number) and on the next start of hugin a new preferences file will be generated.

Other fixes for occurring problems can be found in the Hugin FAQ.

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