[USE CASE] Display large tiled images

[antbrown]

Overview of Use Case
Currently when visitors try to view medium/large tiled images we get timeouts from Cantaloupe generating the tiles. The same happens on https://sandbox.islandora.ca/ after uploading a sample image.

Title (Goal): Provide instructions to encode TIFFs, configure Cantaloupe, setup caching and warm the cache so that tiled images can be served efficiently.

Primary Actors:

• User: wants to view and zoom into tiled images without getting timeouts
• System Administrator: wants to know how to configure and provision the system so that tiles can be generated and cached efficiently

Scope

Architecture

Story:

As a User I want to view a large tiled image and zoom into all the little details without having to wait a long time for each tile to load

Examples:

• Paul Sutherland (client) raised the issue on the mailing list here: https://groups.google.com/g/islandora/c/HY6AgGJK-7s/m/ILq90aIgAQAJ
• The issue was talked about recently on slack: https://islandora.slack.com/archives/CM5PPAV28/p1663855759655659
• Don Richards linked to a very interesting read here: https://www.getty.edu/project-files/iiif_getty_research_report.pdf

What we have done so far:

• We have a script that tries to generate urls for each tile at each zoom level for a TIFF, it then loops through the urls and requests them from Cantaloupe to try and warm the cache (effectively simulating a user panning/zooming around the image)
• Cantaloupe is configured to cache source files and tiles
• Cantaloupe is running on a dedicated server with 4x CPU, 16GB RAM
• We have tried encoding a set of TIFFs from striped to pyramidal using, for example: vips im_vips2tiff CCL-Star-1981-5018-007-015N-02.tif vips_image.tif:lzw,tile:512x512,pyramid

Questions:

• Is it possible to put a frontend cache, eg: varnish, in front of Cantaloupe?
• Does anyone know of example Islandora instances which are serving large numbers of tiled images?
• Have you encountered this issue before? Please +1 or add your voice so we can get an idea of how many people are looking for a solution

[DonRichards]

@antbrown The URLs are part of Cantloupe's API. https://cantaloupe-project.github.io/manual/4.1/endpoints.html

But Cantaloupe has "Source Cache" It should "pre-processed source images onto the filesystem" according to the docs. - https://cantaloupe-project.github.io/manual/4.1/caching.html