GIS Polygon Boundary Creation
4464
£300(approx. $372)
- Posted:
- Proposals: 7
- Remote
- #110627
- Archived
Description
Experience Level: Expert
We have a rudimentary Postcode polygon boundary file built from Ordnance Survey Code-Point OpenData around a year ago and we are now looking for an external GIS partner to manage the updates of this file on an ongoing basis.
Specifically, the process is as follows:
1. To generate a thiessen polygon (through tessellation) around each of the 1.7 million Postcodes in the UK (England, Scotland, Wales and Northern Ireland).
2. We do not expect the boundaries of the polygons to follow physical features such as roads, railways or rivers although if you believe you can enhance the boundaries in this way and within the set budget then we would be very interested.
3. Aggregate the polygons to Postcode Sector level
4. Clip the polygons to a UK coastline which we will supply.
5. Clean the polygons. Due to the process we used we found, particularly at the coastline, polygon slivers appeared which should not be there. In these cases they were merged with neighbouring Postcode polygons. Essentially we are looking for a clean set of contiguous polygons across the UK as much as possible although we acknowledge there will be islands due to the nature of the data. There are also polygons which are fragmented - where possible these polygons need combining to create single polygons or where the polygons are very small they should be merged with a neighbouring or surrounding polygon.
6. Polygons should also be checked for integrity - no overlaps, wholes or slivers in the polygons.
Once the Sector level polygons are complete, we need 2 higher levels of Polygons building simply by merging polygons based on polygon attributes - these will be Districts and Areas.
7. In terms of sizes, the tesselation should create around 1.7 million Postcode polygons but all we need back are:
- approx. 10,000 Postcode Sector polygons
- approx 3,000 Postcode District polygons
- approx. 121 Postcode Area polygons
We can accept the polygon files in either ESRI SHAPE format or MapInfo Interchange format.
This job is for one polygon build but if all goes well we will want the provider to supply updates to this file approximately every 3 months. The current polygon file, Postcode data and coastline can be supplied if required.
Specifically, the process is as follows:
1. To generate a thiessen polygon (through tessellation) around each of the 1.7 million Postcodes in the UK (England, Scotland, Wales and Northern Ireland).
2. We do not expect the boundaries of the polygons to follow physical features such as roads, railways or rivers although if you believe you can enhance the boundaries in this way and within the set budget then we would be very interested.
3. Aggregate the polygons to Postcode Sector level
4. Clip the polygons to a UK coastline which we will supply.
5. Clean the polygons. Due to the process we used we found, particularly at the coastline, polygon slivers appeared which should not be there. In these cases they were merged with neighbouring Postcode polygons. Essentially we are looking for a clean set of contiguous polygons across the UK as much as possible although we acknowledge there will be islands due to the nature of the data. There are also polygons which are fragmented - where possible these polygons need combining to create single polygons or where the polygons are very small they should be merged with a neighbouring or surrounding polygon.
6. Polygons should also be checked for integrity - no overlaps, wholes or slivers in the polygons.
Once the Sector level polygons are complete, we need 2 higher levels of Polygons building simply by merging polygons based on polygon attributes - these will be Districts and Areas.
7. In terms of sizes, the tesselation should create around 1.7 million Postcode polygons but all we need back are:
- approx. 10,000 Postcode Sector polygons
- approx 3,000 Postcode District polygons
- approx. 121 Postcode Area polygons
We can accept the polygon files in either ESRI SHAPE format or MapInfo Interchange format.
This job is for one polygon build but if all goes well we will want the provider to supply updates to this file approximately every 3 months. The current polygon file, Postcode data and coastline can be supplied if required.
Projects Completed
78
Freelancers worked with
53
Projects awarded
66%
Last project
23 May 2023
United Kingdom
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