ORAL PRESENTATION 354 A GRAPH THEORY APPROACH TO ROAD NETWORK GENERALIZATION Abstract
Bibliographic record
Abstract
The development of techniques for the automatic integration of remotely sensed data into a GIS environment is one focus of research at Canada Centre for Remote Sensing. One aspect of this effort is the automatic creation of databases of geographic data: which can be reconfigured on demand to yield the information relevant to a given context, e.g. for map compilation. A theoretical framework is provided by a model developed at CCRS for automated spatial and thematic generalization, and techniques are being · developed for automatic structuring, classification and coding of unstructured road network data into a suitable form supporting generalizations. An appropriate classification of road data must take into account features such as surface type and number of lanes, and also functional aspects such as a road's relative importance in linking a given set of locations. Graph representations offer a convenient · means of handling the topological and associated information describing a road network; and the use of graph theory in supporting network analysis and generalization is briefly reviewed. Graph theoretic techniques, such as the shortest path between network nodes and spanning trees, are then shown to provide a solution to the iinportant problem of deriving measures of the functional relevance of network road segments, given a context defined in terms of a set of points of interest. Thus, for a given context, a ·set of rankings reflecting the importance ' of the 'segments is- created which can serve as the basis for the attenuation of the network to any required degree for use in map density reduction and generalization. Spanning trees can be used in addition to maintain connectivity between destination points during attenuation. Results from a prototype implementation of the network analysis system are presented. Preliminary tests indicate the effectiveness of the analyses: graph theoretic methods allow·the efficient extraction and handling of the pertinent topological properties 'of a network,. and as such naturally support generalization which aimS'to find the essential or representative characteristics ofa data set t'or a given context.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.005 | 0.003 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.118 | 0.017 |
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".