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Feature #574

Updated by Stefan Eichert over 8 years ago

Whitepaper Geometries 


 Content 

 Concept 
 1. What types of physical things with locations are there according to the sources 
 1a. How exactly or fuzzy is their extend defined 
 1b. Which various possibilites can be observed regarding the identification of an physical object with a spatial position 

 Technical Basics 
 2. What types of geometries are needed to map the spatial extend/position of the objects 

 Technical Details 
 3. Tables used to represent the objects and their location 
 4. Queries and Triggers used to update/delete/insert additional/needed information.  

 UI and Userinput 
 5. Buttons and forms 
 5.1. Add Geometry 


 h1. 1. What types of physical things with locations are there according to the sources 

 I. Physical things like buildings, settlements, regions, areas etc. that have or originally had a position in space and a certain extend 
 II. Roads/routes/rivers that What we have or originally had a position in space and a certain extend 
 III. Points where for example an archaeological find has been found. 

 h2. 1a. How exactly or fuzzy is their extend defined 

 Ad. I. and II.: Either the polygon represents the extend=shape of the physical thing  
 or the original (and no longer known) extend is located within a polygon sources (archaeological/written): 
 Also it is possible that there is no extend but only a known centerpoint. 


 h2. 1b. Which various possibilites can -roads/routes/rivers 
 --to be observed regarding the identification of an physical object with a spatial position 

 case 1: The extend is known and can be drawn displayed as a polygon 
 E.g. the shape of a building or the area of excavation or the area of a settlement that can be drawn for example from an aerial photograph or a map. lines/corridors 

 case 2: The extend is not known but known to be within a larger area -physical things with known extend that can fixed location (settlements, buildings, regions) 
 --to be drawn displayed as a polygon 
 E.g a no longer existing settlement that is known to have been situated within a known area for example in a valley between two other known settlements. points/polygons 

 case 3: The extend is not known but known to be -physical things within a larger area with unknown extend that cannot administrative units 
 --to be drawn displayed as a polygon 
 E.g. a no longer existing settlement that is known to have been situated within the historical boundaries of a no longer existing county. 


 case 4: Neither the extend nor a vague position within a reasonable larger area are known. point/polygons 

 In many cases the exact identification of physical things/places mentioned in sources (e.g. in charters or also in archaeological publications) with one certain and still existing physcial entity and its extend is not possible. Therefore it is necessary to allow multiple possibilites to record possible locations of physical things: 
 If a charter for example mentions one church and today two still existing churches might be identified with the one mentioned. In this case the church-entity from the source should be linked to two possible spatial objects. Here they would be two polygons, representing the extend of the respective church. However, any combination of the above mentioned cases (from 1 to 3) must be possible in any number. In theory it must be possible to link e.g. a castle known from a charter to the very extend of a still existing castle and at the same time to a vanished castle that is known to have been located within a certain area and also to another possible location within a certain administrative unit etc. etc. 



 UI: what to draw:  
 1. Point: centerpoint of location. Drawn by user  
 2. Polygon: a) Shape of physical thing b) area in which physical thing is located 

 Backend: what to create:  
 if Polygon is drawn/updated GIS-centerpoint should be triggered 



 3. Line: a) exactly known route b) corridor in which route lies 


 Polygons 

 all at once possible in any combination 
 defined by a certain type or subtype 
 Types: 
 Area of possible localisation (with a certain probability, defined by user) 
 Shape of place: E.g. the outline of a village, a building... = you are certain about the localisation 
 Corridor Polygon: Boundaries of a possible route.. Route must lie within the corridor. 

 Fake: Tools and lines: very small/thin polygons 

 To discuss: more than 1 possible location of 1 physical thing 

 Probability/Certainty of location 

 Centerpoint of place: E.g. the point where a strayfind has been found, like a localisation via GPS... 


 How to implement:  

 1-n connection from place (E53-localisation of place) to postgis table - geometry collection or various tables? 
 Probably better with geometry collection -- all in one table 

 to be continued... 



 





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