ashatora/openlayers
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Use calculateElevation function

Browse Source
This commit is contained in:
mike-000
2021-05-26 13:53:53 +01:00
committed by GitHub
parent 04e323d69e
commit 599e3f18c1
1 changed files with 16 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
examples/shaded-relief.js
View File

@@ -41,6 +41,18 @@ function shade(inputs, data) {
aspect,
cosIncidence,
scaled;
function calculateElevation(pixel) {
// The method used to extract elevations from the DEM.
// In this case the format used is
// red + green * 2 + blue * 3
//
// Other freqquently used methods include the Mapbox format
// (red * 256 * 256 + green * 256 + blue) * 0.1 - 10000
// and the Terrarium format
// (red * 256 + green + blue / 256) - 32768
//
return pixel[0] + pixel[1] * 2 + pixel[2] * 3;
}
for (pixelY = 0; pixelY <= maxY; ++pixelY) {
y0 = pixelY === 0 ? 0 : pixelY - 1;
y1 = pixelY === maxY ? maxY : pixelY + 1;
@@ -54,7 +66,7 @@ function shade(inputs, data) {
pixel[1] = elevationData[offset + 1];
pixel[2] = elevationData[offset + 2];
pixel[3] = elevationData[offset + 3];
z0 = data.vert * (pixel[0] + pixel[1] * 2 + pixel[2] * 3);
z0 = data.vert * calculateElevation(pixel);
// determine elevation for (x1, pixelY)
offset = (pixelY * width + x1) * 4;
@@ -62,7 +74,7 @@ function shade(inputs, data) {
pixel[1] = elevationData[offset + 1];
pixel[2] = elevationData[offset + 2];
pixel[3] = elevationData[offset + 3];
z1 = data.vert * (pixel[0] + pixel[1] * 2 + pixel[2] * 3);
z1 = data.vert * calculateElevation(pixel);
dzdx = (z1 - z0) / dp;
@@ -72,7 +84,7 @@ function shade(inputs, data) {
pixel[1] = elevationData[offset + 1];
pixel[2] = elevationData[offset + 2];
pixel[3] = elevationData[offset + 3];
z0 = data.vert * (pixel[0] + pixel[1] * 2 + pixel[2] * 3);
z0 = data.vert * calculateElevation(pixel);
// determine elevation for (pixelX, y1)
offset = (y1 * width + pixelX) * 4;
@@ -80,7 +92,7 @@ function shade(inputs, data) {
pixel[1] = elevationData[offset + 1];
pixel[2] = elevationData[offset + 2];
pixel[3] = elevationData[offset + 3];
z1 = data.vert * (pixel[0] + pixel[1] * 2 + pixel[2] * 3);
z1 = data.vert * calculateElevation(pixel);
dzdy = (z1 - z0) / dp;