I too like idea to recommend that data producers report positional errors (and I guess other coordinate value errors) between the original data coordinates and the reconstituted coordinates in the `comment` attribute of the subsampled coordinate variables.
Regarding the specification of the computational precision, which is required as input for the method to achieve an accuracy within the errors reported in the comment of the coordinate variable, my preference would still be the `computational_precision` attribute of the interpolation variable. I believe that for our _Lossy Compression by Coordinate Subsampling_ to become popular, it should be easy and straight forward to use, in particular the data uncompression process by the data user. There should be no need for the user to look into the data variable comments, in order to be able to uncompress the data set. The `computational_precision` attribute makes it readable by the software in a safe and automated manner. The reason for this preference is that I have tried out different selections of interpolation method, degree of subsampling (4x4, 8x8, 16x16, 64x16) and computational precision (64-bit, 32-bit floating-point arithmetic) on a test data set. All three components can have a comparable effect on the positional error between the original and the uncompressed file, which I think justifies specifying the computational precision in the same way as we specify the interpolation method and the degree of subsampling. @erget: It is true that the Conventions do not address computational precision, but I guess there are a number of undocumented and implicit assumptions. Say, if you have specified a grid mapping for coordinates represented as 64-bit floating-point, one would assumes that the conversion between the two reference frames have been performed using 64-bit floating-point arithmetic, otherwise significant errors would be introduced. Considering the complexity of what we are doing, I think that stating the computational precision explicitly would be the safest. Best regards, Anders -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://urldefense.us/v3/__https://github.com/cf-convention/cf-conventions/issues/327*issuecomment-876608240__;Iw!!G2kpM7uM-TzIFchu!ksfKQ5_peYUt22QKURjigW55zsFjNbjf8dKi3ksINgQZbN0Bqfiunx_yV-y9LVLt5t8nmB_pHm0$ This list forwards relevant notifications from Github. It is distinct from [email protected], although if you do nothing, a subscription to the UCAR list will result in a subscription to this list. To unsubscribe from this list only, send a message to [email protected].
