Autocomplete polygon tool creates misalignments in existing polygons

[AndrewLawson]

Hi there,

Has anyone else experienced this issue?  I have a colleague who is digitising complex habitat parcels, often using the autocomplete polygon tool, and he is repeatedly finding that previously digitised features within the dataset have subsequently shifted by small amounts, creating misalignments where none previously existed.

I am at a loss to assist him, and have not experienced this issue myself, but he is a capable individual and he feels sure this is not a case of user error.

Thanks for any help

Andrew

[DanPatterson_Retired]

Does the file being edited have a defined coordinate system?  What is the magnitude of the shift?  Is it bigger than floating point representation?  (ie just a smidge or is orders of magnitude bigger.)

[AndrewLawson]

Thanks for your reply. The gaps between features seem to be in the order of several centimetres, and the dataset is set to British National Grid.  My colleague was using the Bing aerial imagery as a backdrop to inform his digitising, so he would have been using a transformation to bring this WGS84 data into alignment with our national grid.

[DarrenWiens2]

Is your colleague editing in a data frame with a different coordinate system than the data? See here for how this can cause alignment issues.