optimized radar image merging

This commit is contained in:
Matt Walsh
2025-05-25 15:17:56 -05:00
parent 8d20f7672c
commit 002e037bbd
2 changed files with 78 additions and 56 deletions

View File

@@ -1,78 +1,106 @@
import * as utils from './radar-utils.mjs';
const radarFullSize = { width: 2550, height: 1600 };
const radarFinalSize = { width: 640, height: 367 };
const fetchAsBlob = async (url) => {
const response = await fetch(url);
return response.blob();
};
onmessage = async (e) => {
const baseMapImage = createImageBitmap(await fetchAsBlob('/images/maps/radar.webp'));
const baseMapImages = new Promise((resolve) => {
fetchAsBlob('/images/maps/radar.webp').then((blob) => {
createImageBitmap(blob).then((imageBitmap) => {
// extract the black pixels to overlay on to the final image (boundaries)
console.time('radar-overlay');
const canvas = new OffscreenCanvas(imageBitmap.width, imageBitmap.height);
const context = canvas.getContext('2d');
context.drawImage(imageBitmap, 0, 0);
const imageData = context.getImageData(0, 0, imageBitmap.width, imageBitmap.height);
// go through the image data and preserve the black pixels, making the rest transparent
for (let i = 0; i < imageData.data.length; i += 4) {
if (imageData.data[i + 0] >= 116 || imageData.data[i + 1] >= 116 || imageData.data[i + 2] >= 116) {
// make it transparent
imageData.data[i + 3] = 0;
}
}
// write the image data back
context.putImageData(imageData, 0, 0);
console.timeEnd('radar-overlay');
resolve({
fullMap: imageBitmap,
overlay: canvas,
});
});
});
});
onmessage = async (e) => {
const {
url, index, RADAR_HOST, OVERRIDES, radarSourceXY, sourceXY, offsetX, offsetY,
url, RADAR_HOST, OVERRIDES, radarSourceXY, sourceXY, offsetX, offsetY,
} = e.data;
// get the image
const modifiedRadarUrl = OVERRIDES.RADAR_HOST ? url.replace(RADAR_HOST, OVERRIDES.RADAR_HOST) : url;
const radarResponsePromise = fetch(modifiedRadarUrl);
// calculate offsets and sizes
const width = 2550;
const height = 1600;
const radarOffsetX = 120;
const radarOffsetY = 70;
const radarSourceX = Math.round(radarSourceXY.x / 2);
const radarSourceY = Math.round(radarSourceXY.y / 2);
const radarSource = {
width: 240,
height: 163,
x: Math.round(radarSourceXY.x / 2),
y: Math.round(radarSourceXY.y / 2),
};
// create destination context
const baseCanvas = new OffscreenCanvas(640, 367);
const baseContext = baseCanvas.getContext('2d', { alpha: false });
const baseCanvas = new OffscreenCanvas(radarFinalSize.width, radarFinalSize.height);
const baseContext = baseCanvas.getContext('2d');
baseContext.imageSmoothingEnabled = false;
// create working context for manipulation
const radarCanvas = new OffscreenCanvas(width, height);
const radarContext = radarCanvas.getContext('2d', { alpha: false });
const radarCanvas = new OffscreenCanvas(radarFullSize.width, radarFullSize.height);
const radarContext = radarCanvas.getContext('2d');
radarContext.imageSmoothingEnabled = false;
// get the image
const modifiedUrl = OVERRIDES.RADAR_HOST ? url.replace(RADAR_HOST, OVERRIDES.RADAR_HOST) : url;
console.time(`Radar-${index}-fetch`);
const response = await fetch(modifiedUrl);
console.timeEnd(`Radar-${index}-fetch`);
// get the base map
const baseMaps = await baseMapImages;
baseContext.drawImage(baseMaps.fullMap, sourceXY.x, sourceXY.y, offsetX * 2, offsetY * 2, 0, 0, radarFinalSize.width, radarFinalSize.height);
// test response
if (!response.ok) throw new Error(`Unable to fetch radar error ${response.status} ${response.statusText} from ${response.url}`);
const radarResponse = await radarResponsePromise;
if (!radarResponse.ok) throw new Error(`Unable to fetch radar error ${radarResponse.status} ${radarResponse.statusText} from ${radarResponse.url}`);
// get the blob
console.time(`Radar-${index}-blob`);
const radarImgBlob = await response.blob();
console.timeEnd(`Radar-${index}-blob`);
const radarImgBlob = await radarResponse.blob();
// assign to an html image element
console.time(`Radar-${index}-loadimg-element`);
const radarImgElement = await createImageBitmap(radarImgBlob);
console.timeEnd(`Radar-${index}-loadimg-element`);
// draw the entire image
radarContext.clearRect(0, 0, width, 1600);
console.time(`Radar-${index}-drawimage`);
radarContext.drawImage(radarImgElement, 0, 0, width, 1600);
console.timeEnd(`Radar-${index}-drawimage`);
// get the base map
console.time(`Radar-${index}-drawbasemap`);
baseContext.drawImage(await baseMapImage, sourceXY.x, sourceXY.y, offsetX * 2, offsetY * 2, 0, 0, 640, 367);
console.timeEnd(`Radar-${index}-drawbasemap`);
// crop the radar image
const cropCanvas = new OffscreenCanvas(640, 367);
const cropContext = cropCanvas.getContext('2d', { willReadFrequently: true });
cropContext.imageSmoothingEnabled = false;
console.time(`Radar-${index}-copy-radar`);
cropContext.drawImage(radarCanvas, radarSourceX, radarSourceY, (radarOffsetX * 2), Math.round(radarOffsetY * 2.33), 0, 0, 640, 367);
console.timeEnd(`Radar-${index}-copy-radar`);
// clean the image
console.time(`Radar-${index}-clean-image`);
utils.removeDopplerRadarImageNoise(cropContext);
console.timeEnd(`Radar-${index}-clean-image`);
radarContext.clearRect(0, 0, radarFullSize.width, radarFullSize.height);
radarContext.drawImage(radarImgElement, 0, 0, radarFullSize.width, radarFullSize.height);
// merge the radar and map
console.time(`Radar-${index}-merge`);
utils.mergeDopplerRadarImage(baseContext, cropContext);
console.timeEnd(`Radar-${index}-merge`);
// crop the radar image without scaling
const croppedRadarCanvas = new OffscreenCanvas(radarSource.width, radarSource.height);
const croppedRadarContext = croppedRadarCanvas.getContext('2d');
croppedRadarContext.imageSmoothingEnabled = false;
croppedRadarContext.drawImage(radarCanvas, radarSource.x, radarSource.y, croppedRadarCanvas.width, croppedRadarCanvas.height, 0, 0, croppedRadarCanvas.width, croppedRadarCanvas.height);
// clean the image
utils.removeDopplerRadarImageNoise(croppedRadarContext);
// stretch the radar image
const stretchCanvas = new OffscreenCanvas(radarFinalSize.width, radarFinalSize.height);
const stretchContext = stretchCanvas.getContext('2d', { willReadFrequently: true });
stretchContext.imageSmoothingEnabled = false;
stretchContext.drawImage(croppedRadarCanvas, 0, 0, radarSource.width, radarSource.height, 0, 0, radarFinalSize.width, radarFinalSize.height);
// put the radar on the base map
baseContext.drawImage(stretchCanvas, 0, 0);
// put the road/boundaries overlay on the map
baseContext.drawImage(baseMaps.overlay, sourceXY.x, sourceXY.y, offsetX * 2, offsetY * 2, 0, 0, radarFinalSize.width, radarFinalSize.height);
const processedRadar = baseCanvas.transferToImageBitmap();

View File

@@ -1,7 +1,6 @@
// current weather conditions display
import STATUS from './status.mjs';
import { DateTime } from '../vendor/auto/luxon.mjs';
import { loadImgElement } from './utils/image.mjs';
import { text } from './utils/fetch.mjs';
import WeatherDisplay from './weatherdisplay.mjs';
import { registerDisplay, timeZone } from './navigation.mjs';
@@ -110,10 +109,8 @@ class Radar extends WeatherDisplay {
// Load the most recent doppler radar images.
const radarInfo = await Promise.all(urls.map(async (url, index) => {
console.time(`Radar-${index}`);
const processedRadar = await this.workers[index].processRadar({
url,
index,
RADAR_HOST,
OVERRIDES,
sourceXY,
@@ -136,16 +133,13 @@ class Radar extends WeatherDisplay {
zone: 'UTC',
}).setZone(timeZone());
console.time(`Radar-${index}-transfer-canvas`);
const onscreenCanvas = document.createElement('canvas');
onscreenCanvas.width = 640;
onscreenCanvas.height = 367;
onscreenCanvas.width = processedRadar.width;
onscreenCanvas.height = processedRadar.height;
const onscreenContext = onscreenCanvas.getContext('bitmaprenderer');
onscreenContext.transferFromImageBitmap(processedRadar);
const elem = this.fillTemplate('frame', { map: { type: 'canvas', canvas: onscreenCanvas } });
console.timeEnd(`Radar-${index}-transfer-canvas`);
console.timeEnd(`Radar-${index}`);
return {
time,
elem,
@@ -184,7 +178,7 @@ class Radar extends WeatherDisplay {
// create a radar worker with helper functions
const radarWorker = () => {
// create the worker
const worker = new Worker('scripts/modules/radar-worker.mjs', { type: 'module' });
const worker = new Worker(new URL('./radar-worker.mjs', import.meta.url), { type: 'module' });
const processRadar = (url) => new Promise((resolve, reject) => {
// prepare for done message