convert map boundaries into VertexBuffer with a shader on a Layer

[djhoese]

In GitLab by @rayg-ssec on Sep 2, 2015, 12:33

• convert lat/lon map boundary via PROJ4 into a projected coordinate VBO backed by a gloo.Program, such that political and geographical boundaries can be plotted with selectable line color/weight/alpha, as a Layer subclass e.g. PoliticalBoundariesVectorLayer. Use data from Matplotlib or elsewhere.

[djhoese]

In GitLab by @djhoese on Sep 8, 2015, 14:39

I've talked with Martin Raspaud of the pytroll team and done some googling and I think the best way to do this is to use the NetCDF or shape files that can be found here: https://www.ngdc.noaa.gov/mgg/shorelines/gshhs.html

Shape files and binary files have links on the SOEST server page.

I asked Martin if he thinks shape files would be easier to use since NetCDF might be easier for us to distribute (netcdf4-python) given the data files that are involved in the data we are displaying. He said he doesn't think it matters. Shapefiles are still widely used in the GIS community.

I'd like to continue working on this ticket.

[djhoese]

In GitLab by @djhoese on Sep 8, 2015, 15:15

Just found this nice quote on one of the related pages:

We discourage anyone from using the netCDF version for custom programming applications [due to complexity and lack of documentation, mostly]

[djhoese]

In GitLab by @djhoese on Sep 8, 2015, 16:10

Added Wiki page here

[djhoese]

In GitLab by @djhoese on Sep 25, 2015, 12:21

I've updated the wiki page to explain what I've learned about Natural Earth. I've also added a layer rep to CSPOV that can handle loading shapefiles as a set of polygons. At first I had performance problems because the shape files had a lot of little islands and other shapes so creating a LineVisual object for each one was a big problem. I updated the code so it acts as one line visual program with individual line segments. This doubles (if not more) the GPU memory that would normally be needed (100s of KBs), but is a ridiculous performance increase.

These layers are not tiled and do not support the idea of only loading what is being shown since the amount of memory relative to images is small. It also is not an easy task to make sure that lines are drawn properly when one of the end points of a line segment is outside the viewing area.

[djhoese]

In GitLab by @djhoese on Oct 1, 2018, 16:50

mentioned in commit f8d2a69