ObsCore update discussion : adding Axes information in Obscore table

[Patrick Dowler]

On 24/04/15 11:15 AM, Louys Mireille wrote:
> if t_dim > 20,  I may be interested in this time serie aspect: enough
> time samples , or I may discard it : not enough time samples...

This is the kind of scenario where giving the number of samples is 
really useful to the user because they will have some potentially 
arbitrary number which they think makes some data a useful time series 
or not. Providers can't know what that "too small" number is so a 
"label" approach is a little too simplistic to work.

 From the provider point of view, they also don't really know how to 
draw the line when the number of samples is small-ish, so they won't 
know when to say that something has a "useful" time axis or not. For 
example, we have data (WirCam data from CFHT) where the raw data usually 
has t_dim = 4. That's not really a time series, but the product as-is 
isn't exactly a 2d image either. It's mostly only good for stacking to 
make an image, which might lead someone to want to "just say it is an 
image" and that will be true until someone figures out a way to exploit 
that t_dim=4 for something else... or t_dim=8, or whatever.

We also have other kinds of data with edge-case values, eg e_dim=2 or 4. 
I'm guessing that typical IFU datacubes would have modest values of 
s_dim1 and s_dim2, so this helps users quantitatively differentiate them 
from really big datacubes*


my 2c,



*logically big - don't bring up access_estsize to say "can already do 
this" and say we should keep discovery and access separate... :-)

-- 

Patrick Dowler
Canadian Astronomy Data Centre
National Research Council Canada
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