opengeospatial / dggs-4-axis-aligned

0 stars 0 forks source link

Flexible axis ratio not allowed? #7

Open jerstlouis opened 3 years ago

jerstlouis commented 3 years ago

The GNOSISGlobalGrid and CDBGlobalGrid have varying latitude / longitude axis ratios to approximate equal area cells.

It appears that the AA DGGS standard currently expects this ratio to be fixed.

This is a major issue and unnecessary limitation in my opinion.

7.6.1 Tesselation Overview states:

Each axis is partitioned independently and has its tessellation pattern and ratio

Since a ratio is a comparison is between two number, what exactly does this mean, especially if you have more than two axes?

There might also be an issue with partitioned independently in those variable width tesselations where e.g. how to partition the longitude might depends on the latitude.

It might also be worth to note and validate that in those variable width TileMatrixSets different cells of the same hierarchy level might have a different number of children as a result.

Same issue in Requirement Test A.8

Also in Table 6 the name uses AxisRation while the definition says AxisRatio without the n.