Using the N5 tile source

[John Roche]

Hi,

I have to import tiles that I believe are in N5 tile format 

but there is an issue I get when I change the tile source to N5

from the errors I get from the log file I get 

Error: Custom { kind: Other, error: StringError("JsValue(SyntaxError: Unexpected end of JSON input\n        SyntaxError: Unexpected end of JSON input)") } User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36 Stacktrace: Error: Custom { kind: Other, error: StringError("JsValue(SyntaxError: Unexpected end of JSON input\n        SyntaxError: Unexpected end of JSON input)") }
    at __wbg_new_098793756709d10a (http://10.28.41.235/catmaid/static/libs/n5-wasm/n5_wasm.js:283:26)
    at <futures::future::map_err::MapErr<A,F> as futures::future::Future>::poll::h719eed576f850799 (wasm-function[153]:1438)
    at wasm_bindgen_futures::_future_to_promise::Package::poll::h14e20d21c038b182 (wasm-function[239]:667)
    at <wasm_bindgen_futures::_future_to_promise::Package as futures::task_impl::Notify>::notify::{{closure}}::h2de9e6c653ab4041 (wasm-function[550]:60)
    at wasm_bindgen::convert::closures::invoke1_mut::hfc4b8963a63dfd8f (wasm-function[652]:17)
    at Function.cb (http://10.28.41.235/catmaid/static/libs/n5-wasm/n5_wasm.js:541:20)

Has anyone successfully import N5 tiles before?

John

[Andrew Champion]

Hi John,

It's somewhat surprising if you have an N5 volume, as it's not yet widely used. The N5 source does work, but is still a bit tricky to get working. The error you're receiving is generic; it just means the tile source can't read one of the N5's `attributes.json` files, which could be because the source URL is wrong, the data is not in N5 format, etc. Can you see in the browser network inspector what request is causing the error and what the request headers are?

For more on getting started with the N5 source type, see the N5 source type documentation [0] and the troubleshooting comments on this pull request [1].

Best,

Andrew Champion

[0] https://catmaid.readthedocs.io/en/stable/tile_sources.html#n5-image-blocks

[1] https://github.com/catmaid/CATMAID/pull/1827#issuecomment-456903868