Increase grid to 0.125 degrees with smooth canvas overlay

Replace circle markers with a canvas tile layer that renders smooth,
flowing colored regions using bilinear interpolation between grid
points. Colors interpolate between tiers for gradients. ~95k grid
points at 0.125 degree resolution with wgrib2 extraction.
This commit is contained in:
Graham McIntire 2026-03-31 08:52:07 -05:00
parent becdf89978
commit 66639e3717
No known key found for this signature in database
GPG key ID: F4ABF488E6029E59
3 changed files with 126 additions and 44 deletions

View file

@ -1,6 +1,5 @@
export const PropagationMap = {
mounted() {
// Center on DFW airport, ~500 mile radius
this.map = L.map(this.el, {
center: [32.897, -97.038],
zoom: 7,
@ -13,14 +12,15 @@ export const PropagationMap = {
maxZoom: 19
}).addTo(this.map)
this.scoreLayer = L.layerGroup().addTo(this.map)
this.scoreOverlay = null
this.scores = []
this.colorScale = [
{ min: 80, color: "#00ffa3" },
{ min: 65, color: "#7dffd4" },
{ min: 50, color: "#ffe566" },
{ min: 33, color: "#ff9044" },
{ min: 0, color: "#ff4f4f" }
{ min: 80, r: 0, g: 255, b: 163 }, // EXCELLENT - green
{ min: 65, r: 125, g: 255, b: 212 }, // GOOD - light green
{ min: 50, r: 255, g: 229, b: 102 }, // MARGINAL - yellow
{ min: 33, r: 255, g: 144, b: 68 }, // POOR - orange
{ min: 0, r: 255, g: 79, b: 79 } // NEGLIGIBLE - red
]
const initialScores = JSON.parse(this.el.dataset.scores || "[]")
@ -30,6 +30,7 @@ export const PropagationMap = {
this.renderScores(scores)
})
// Legend
const legend = L.control({ position: "bottomright" })
legend.onAdd = () => {
const div = L.DomUtil.create("div")
@ -51,37 +52,118 @@ export const PropagationMap = {
},
renderScores(scores) {
this.scoreLayer.clearLayers()
scores.forEach(({ lat, lon, score }) => {
const color = this.scoreColor(score)
const circle = L.circleMarker([lat, lon], {
radius: 6,
fillColor: color,
fillOpacity: 0.7,
color: color,
weight: 0
})
circle.bindPopup(
`<strong>Score: ${score}/100</strong><br>${this.scoreTier(score)}<br>` +
`<small>${lat.toFixed(3)}\u00b0N, ${Math.abs(lon).toFixed(3)}\u00b0W</small>`
)
this.scoreLayer.addLayer(circle)
})
},
scoreColor(score) {
for (const tier of this.colorScale) {
if (score >= tier.min) return tier.color
this.scores = scores
if (this.scoreOverlay) {
this.map.removeLayer(this.scoreOverlay)
}
return "#ff4f4f"
if (scores.length === 0) return
// Build a lookup grid for interpolation
this.gridLookup = new Map()
scores.forEach(({ lat, lon, score }) => {
this.gridLookup.set(`${lat.toFixed(3)},${lon.toFixed(3)}`, score)
})
// Create a custom canvas overlay
const self = this
this.scoreOverlay = L.GridLayer.extend({
createTile(coords) {
const tile = document.createElement("canvas")
const size = this.getTileSize()
tile.width = size.x
tile.height = size.y
const ctx = tile.getContext("2d")
const step = 0.125
const nwPoint = coords.scaleBy(size)
const sePoint = nwPoint.add(size)
const nw = this._map.unproject(nwPoint, coords.z)
const se = this._map.unproject(sePoint, coords.z)
// Pixel size in degrees
const latPerPx = (nw.lat - se.lat) / size.y
const lonPerPx = (se.lng - nw.lng) / size.x
// Draw cells - each pixel block maps to a grid point
const cellPxX = Math.max(1, Math.ceil(step / lonPerPx))
const cellPxY = Math.max(1, Math.ceil(step / Math.abs(latPerPx)))
for (let py = 0; py < size.y; py += cellPxY) {
for (let px = 0; px < size.x; px += cellPxX) {
const lat = nw.lat - py * Math.abs(latPerPx)
const lon = nw.lng + px * lonPerPx
const score = self.interpolateScore(lat, lon, step)
if (score !== null) {
const color = self.scoreColorRGB(score)
ctx.fillStyle = `rgba(${color.r},${color.g},${color.b},0.55)`
ctx.fillRect(px, py, cellPxX, cellPxY)
}
}
}
return tile
}
})
this.scoreOverlay = new (this.scoreOverlay)({ opacity: 1.0 })
this.scoreOverlay.addTo(this.map)
},
scoreTier(score) {
if (score >= 80) return "EXCELLENT"
if (score >= 65) return "GOOD"
if (score >= 50) return "MARGINAL"
if (score >= 33) return "POOR"
return "NEGLIGIBLE"
interpolateScore(lat, lon, step) {
// Snap to nearest grid point
const rlat = (Math.round(lat / step) * step).toFixed(3)
const rlon = (Math.round(lon / step) * step).toFixed(3)
const key = `${rlat},${rlon}`
if (this.gridLookup.has(key)) return this.gridLookup.get(key)
// Try bilinear interpolation from 4 surrounding points
const lat0 = Math.floor(lat / step) * step
const lat1 = lat0 + step
const lon0 = Math.floor(lon / step) * step
const lon1 = lon0 + step
const s00 = this.gridLookup.get(`${lat0.toFixed(3)},${lon0.toFixed(3)}`)
const s10 = this.gridLookup.get(`${lat1.toFixed(3)},${lon0.toFixed(3)}`)
const s01 = this.gridLookup.get(`${lat0.toFixed(3)},${lon1.toFixed(3)}`)
const s11 = this.gridLookup.get(`${lat1.toFixed(3)},${lon1.toFixed(3)}`)
// Need at least 2 corners to interpolate
const corners = [s00, s10, s01, s11].filter(s => s !== undefined)
if (corners.length < 2) return null
if (corners.length === 4) {
const tLat = (lat - lat0) / step
const tLon = (lon - lon0) / step
return Math.round(
s00 * (1 - tLat) * (1 - tLon) +
s10 * tLat * (1 - tLon) +
s01 * (1 - tLat) * tLon +
s11 * tLat * tLon
)
}
// Fallback: average available corners
return Math.round(corners.reduce((a, b) => a + b, 0) / corners.length)
},
scoreColorRGB(score) {
// Interpolate between tier colors for smooth gradients
for (let i = 0; i < this.colorScale.length - 1; i++) {
const upper = this.colorScale[i]
const lower = this.colorScale[i + 1]
if (score >= lower.min) {
const range = upper.min - lower.min
const t = Math.min(1, (score - lower.min) / range)
return {
r: Math.round(lower.r + (upper.r - lower.r) * t),
g: Math.round(lower.g + (upper.g - lower.g) * t),
b: Math.round(lower.b + (upper.b - lower.b) * t)
}
}
}
const last = this.colorScale[this.colorScale.length - 1]
return { r: last.r, g: last.g, b: last.b }
},
destroyed() {

View file

@ -1,13 +1,13 @@
defmodule Microwaveprop.Propagation.Grid do
@moduledoc "CONUS grid definition for propagation scoring. 0.5 degree resolution (~55 km)."
@moduledoc "CONUS grid definition for propagation scoring. 0.125 degree resolution (~14 km)."
@lat_min 25.0
@lat_max 50.0
@lon_min -125.0
@lon_max -66.0
@step 0.5
@step 0.125
@doc "Returns all grid points as `{lat, lon}` tuples covering CONUS at 0.5 degree spacing."
@doc "Returns all grid points as `{lat, lon}` tuples covering CONUS at 0.125 degree spacing."
def conus_points do
for lat <- float_range(@lat_min, @lat_max, @step),
lon <- float_range(@lon_min, @lon_max, @step) do

View file

@ -4,7 +4,7 @@ defmodule Microwaveprop.Propagation.GridTest do
alias Microwaveprop.Propagation.Grid
describe "conus_points/0" do
test "generates grid at 0.5 degree resolution" do
test "generates grid at 0.125 degree resolution" do
points = Grid.conus_points()
assert length(points) > 5000
assert length(points) < 100_000
@ -17,10 +17,10 @@ defmodule Microwaveprop.Propagation.GridTest do
end)
end
test "points are on 0.5 degree grid" do
test "points are on 0.125 degree grid" do
Enum.each(Grid.conus_points(), fn {lat, lon} ->
assert Float.round(lat * 2, 0) == lat * 2
assert Float.round(lon * 2, 0) == lon * 2
assert Float.round(lat * 8, 0) == lat * 8
assert Float.round(lon * 8, 0) == lon * 8
end)
end
@ -39,8 +39,8 @@ defmodule Microwaveprop.Propagation.GridTest do
end
describe "step/0" do
test "returns 0.5" do
assert Grid.step() == 0.5
test "returns 0.125" do
assert Grid.step() == 0.125
end
end