celutz/INSTALL.md

Installing celutz

System requirements

• Python version 2 (at least 2.6) or version 3 (at least 3.2)
• At least 10 GB of disk space. You should provision 100 MB for each panorama: panoramic pictures can be pretty big to start with, and celutz generates a lot of tiles during the initial upload.
• At least 1.5G of RAM, mainly for tile generation. If you generate tiles on another computer, then you need much less, probably as little as 512 MB of RAM. Celutz is a quite simple Django application.
• a fast CPU, again for tile generation. Having multiple CPU will not be useful in most cases.

Installation

Celutz is a fairly standard Django application: refer to the Django documentation for deployment methods. The initial installation should look like this:

virtualenv ~/mycelutzvenv
. ~/mycelutzvenv/bin/activate
pip install -r requirements.txt
# Configure database if needed
python manage.py migrate
python manage.py createsuperuser

One specific information: you really want to serve the media/ directory with a real webserver, and not with Django itself. Hundreds of tiles (small image files) will be served from this directory each time a client visualises a panorama.

You probably also want to configure your webserver to allow to send very large files in a POST request. An upper limit of 200 MB should be enough, even for very large pictures in raw format.

Tile generation

Tile generation uses Celery, because it is quite a heavy task CPU-wise.

To launch a celery worker while developping, run this in your virtualenv:

celery -c 1 -A ztulec.celery worker --loglevel=info

This tells celery to handle at most one task at a time: -c 1. Indeed, generating tiles for a single panorama can take quite a lot of RAM. If you have enough RAM (2GB+) and multiple CPU, you can increase this parameter to generate tiles for multiple panoramas in parallel.

The default parameters use the Django database as a message queue, to ask a celery woker to generate tiles for a panorama. This is far from efficient, but since there are very few messages, it is not worth the trouble to configure a real message queue such as RabbitMQ.