I may have found a small bug that relates to arc's within a polygon.
We have a layer that is created by buffering point features. The resulting polygon dataset consists of features made of a single arc segment to create a circle.
When we share this dataset through Open Data, after downloading the dataset into a shapefile (using a local projection) or as a kml file the features end up downloading and displaying as an ellipse instead of a circle.
You can try downloading the dataset yourself from our test open data site
They seem to display in the map view in Open Data correctly, its only after downloading that there is an issue.
I can get around the issue by generalising the features to turn each circle into lots of straight line segments, which do then download correctly. It only seems to be arcs that are not downloading correctly. I have also only tested polygons, I haven't tried line segments with arcs. You can download the generalised version here to compare to the data made up of arcs above.
I've attached a screenshot. The black circles are the downloaded features after being generalised into straight line segments and the orange ellipses are the downloaded features when made up of an arc.
Hi Malcolm, one of the libraries we use under the hood for downloads does not currently support arcs. An upgraded version does, but we are not ready to move to it. We should definitely doc this. I'll update you when we have support for this feature type.