Alignment of XIXth century cadasters

Introduction

About a thousand of French napoleonian cadasters have been scanned and need from now to be aligned. A lot of different cities are included in this catalogue as La Rochelle, Bordeaux, Lyon, Lille, Le Havre and also cities that are no longer under French juridiction as Rotterdam.

Based on the work that had been done by the Venice Time Machine project, the idea is to attach every maps from each city in

Organisation

Project first steps

Methods exploration on Berney's cadaster

For the primary research of methods to reattach cadastral maps, the so called cadastre Berney from Lausanne has been used, as long as the ground truth for this particular case is known and lot of processing steps (as lines and classes predictions) have already been made. The first exercise has been made on the two first maps, using the lines prediction files. The quandary was to be able to detect the common parts of these two maps, in this case the Rue Pépinet and the top of Rue du petit chêne. Many different methods have been tested for that task, mainly with help of the openCV python library.

(TODO : lister brièvement toutes les méthodes)

First reattachment of two cadastral maps

The method that gave the most satisfying results (in terms of final output and computation time) was the template matching. The strategy is to cut a template in one of the maps and find the best match in the other one. Attaching the two maps together is then an almost straightforeward task, as long as the lines prediction files are only black (0) or white (255) pixels, and the final result is just the sum of the two of them adapted with the best matching position.

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Automatisation process

After this liminary result, a lot of question were nevertheless still to be answered. For example, is the orientation of our maps precisely in the North direction ? Will it be possible to have an explicit order of maps reattachment ? Will the matching score be as good in the countryside as it was in the city ? Is the scale homogenous within an entire city ? Or what criteria could be used to automatise the template selection ?

Final milestones of semester

	Objective
Week 11	Extract lines on a first set of cadastral maps (La Rochelle or Bordeaux)
Week 12	Test pipeline on the new extracted lines files
Week 13	Adapt our model or extend it on other cities
Week 14	Final presentation