Base64Geo: an efficient data structure and transmission format for large, dense, scalar GIS datasets
Bibliographic record
Abstract
We describe Base64Geo, a data structure and transmission format for large-scale, dense, scalar GIS datasets. Base64Geo encodes a rectangular grid of scalar GIS values as an array of strings, where each character is in the range [0 − 9A − Z a − z + /]. Each string represents the values on a specific latitude value, read west to east; the strings themselves are arranged south to north. The resulting structure gives a wire format for data transmission that is two orders of magnitude more efficient than standard GIS and a compact database structure that is searched with simple string operations. Disk dataset size is reduced by an order of magnitude over a corresponding CSV structure, and by two orders of magnitude over an indexed GIS database. Search times on the string-based Base64Geo dataset are an order of magnitude smaller than search times from a quad-tree based searcher on the same dataset.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.014 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.004 | 0.010 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.007 |
| Open science | 0.004 | 0.005 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.029 | 0.023 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".