Range measured: level 0, sky region +365760..+388880, 23120 bytes.
Method: Pearson correlation between the byte sequence and itself at
increasing lag, against a shuffled control. This asks whether consecutive
records are related, which the position-wise distinct-value counts could not
show.
lag 1 +0.050 lag 256 -0.044
lag 4 +0.560 lag 512 +0.304
lag 8 +0.746 lag 1024 +0.247
lag 16 +0.666 lag 2048 +0.079
lag 32 +0.602 shuffled +0.003
lag 64 +0.432
lag 128 +0.140
The profile peaks at lag 8, decays to a zero crossing near 256, then rises
again to a second smaller peak at 512 before decaying. So records are related
within themselves and repeat every 64 records.
This settles the earlier "no constant substructure" reading. The records share
no fixed fields, but they are not independent either, and that was the thing
the distinct-value counts were failing to capture.
Slowly varying values, related within a record, repeating every 64 records, is
the shape of a keyframe or lookup table -- which is what sky data should be,
where a colour or fog parameter is sampled rather than computed per vertex.
Still not decoded: nothing names the values or the sampling. But the shape is
now known well enough for a decode attempt to aim at, rather than to hunt.
ReaperOfVeriod
b5edbd1810