Comments (5)
It seems that you are computing the contours on the spherical coordinates, then project the resulting polygons. But this creates issues with the holes. If you changed the order of operations (first project, then compute the contours), it would work. I'm sending you a suggestion.
See also https://observablehq.com/@d3/cloud-contours and https://observablehq.com/@fil/netcdf
from d3-contour.
It seems that you are computing the contours on the spherical coordinates, then project the resulting polygons. But this creates issues with the holes. If you changed the order of operations (first project, then compute the contours), it would work. I'm sending you a suggestion.
See also https://observablehq.com/@d3/cloud-contours and https://observablehq.com/@fil/netcdf
Thanks very much for your speedy and professional advice, I'm reading your code now, may get back to you if any further help needed.
Wish you a nice weekend ahead.
from d3-contour.
In the data source(contours.json), masked area(land) is set -1e20.
When I change -1e20 to -999, the chart becomes perfect.
I don't know why this value affect the contour polygons.
from d3-contour.
Ah, true:
contours = d3.contours()
.size([data.width, data.height])
.thresholds(thresholds)(varData.values.map(d => Math.max(-1e13, d)))
is correct, but with 1e-14 it's broken:
contours = d3.contours()
.size([data.width, data.height])
.thresholds(thresholds)(varData.values.map(d => Math.max(-1e14, d)))
from d3-contour.
I suspect that this is related to numerical instability and I think it’s unlikely that we would implement a fully robust algorithm. Maybe we can at least guarantee consistency with d3.polygonArea though.
from d3-contour.
Related Issues (20)
- Release d3-array v2 compatible version? HOT 2
- hole issue in contour HOT 5
- Arrows using elevation value for any point(x, y) in contour chart HOT 5
- GeoJSON Geometry which is generated by d3.contour displays wrong HOT 3
- output data has index which is not exist in input data HOT 2
- Feature request: contour labels HOT 2
- smoothing removes line segements HOT 1
- Buggy input check in density size setter.
- Improve slow computations for large images HOT 2
- Handle Null values in grid HOT 9
- Dependencies HOT 3
- Support fractional bandwidths. HOT 2
- [feature]: cellSize(0.5) would work well in d3.contourDensity() HOT 1
- Support curvilinear grids HOT 11
- Sometimes the lowest threshold is missing
- Bug HOT 2
- Breaking change with contour-density thresholds starting from v3.0.2 HOT 2
- isobands?
- Don’t round the corners HOT 8
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from d3-contour.