cuspatial icon indicating copy to clipboard operation
cuspatial copied to clipboard

[FEA] High-accuracy re-projection

Open thomcom opened this issue 4 years ago • 3 comments

The second ask from @MurrayData. Perhaps you could be more specific?

thomcom avatar Sep 11 '19 15:09 thomcom

High accuracy coordinate projection uses high precision formulae, iterative (in case of E/N to Lat/Lon), to provide surveying & civil engineering quality coordinate conversion. It is used in conjunction with transformations where necessary.

These formulae take into account the eccentricity of the Earth and other factors.

GIS systems, and many off the shelf Python libraries, use simpler approximate formulae for speed. These are ok for most purposes such as overview maps (e.g. election results) but in UK they have an RMS error of +/- 7m (23 ft) and can be up to 20m (70ft) out in places.

In my work I am labelling satellite imagery from ESA and NASA, for deep learning models, which uses the UTM coordinate system combined with labels from UK surveys that are in the OSGB36 BNG system. I need high accuracy to ensure that the labels are accurately placed on the images for object detection and image classification.

These 2 guides explain more with worked examples. Although written for UK, the techniques work for Transverse Mercator type east/north coordinate systems.

A_Guide_to_Coordinate_Systems_in_Great_Britain.pdf

Transformations_and_OSGM15_User_Guide.pdf

For Conical coordinate system used in USA, France, Australia and New Zealand, different formulae area needed.

This explains more with formulae:

https://www.linz.govt.nz/data/geodetic-system/coordinate-conversion/geodetic-datum-conversions/equations-used-datum

Again, happy to share code. I already have these implemented.

MurrayData avatar Sep 12 '19 08:09 MurrayData

This issue has been marked stale due to no recent activity in the past 30d. Please close this issue if no further response or action is needed. Otherwise, please respond with a comment indicating any updates or changes to the original issue and/or confirm this issue still needs to be addressed. This issue will be marked rotten if there is no activity in the next 60d.

github-actions[bot] avatar Feb 16 '21 20:02 github-actions[bot]

This issue has been marked rotten due to no recent activity in the past 90d. Please close this issue if no further response or action is needed. Otherwise, please respond with a comment indicating any updates or changes to the original issue and/or confirm this issue still needs to be addressed.

github-actions[bot] avatar Feb 16 '21 20:02 github-actions[bot]