GeoJSON support #890

mramato · 2013-06-20T21:48:20Z

Add GeoJsonDataSource which as the name implies is a DataSource object which supports GeoJSON. The only aspect of the specification that we do not currently support is holes in polygons. This is a limitation of the DynamicScene layer which must be corrected first (I'll be writing an issue for it).
Hook it up to viewerDragDropMixin and the Cesium Viewer source query parameter.
Add a ConstantProperty which makes it easy to specify static values for DynamicScene objects.
Since GeoJSON does not include styling information, I provide user-modifiable default styling. People with an eye for such things may want to check it out and offer suggestions.

Have GeoJsonDataSource use private versions of them instead until I do them "for real".

mramato · 2013-06-24T13:16:54Z

@shunter, you know you are dying to review this. 😉

@emackey and @hpinkos, you have the best eyes for style around here. Any comments on the default styling?

emackey · 2013-06-24T14:06:56Z

Apps/CesiumViewer/CesiumViewer.js

@@ -50,6 +52,10 @@ define([
        window.alert(e);
    });

+    function endsWith(str, suffix) {
+        return str.indexOf(suffix, str.length - suffix.length) !== -1;


Does this work even if suffix is longer than str?

Yes. The value of the second argument can be positive or negative and if suffix is longer it's impossible for this function to equal anything other than -1. However, your question brings up a good point, I don't need str.length - suffix.length because simply -suffix.length will work exactly the same.

emackey · 2013-06-24T14:16:01Z

Since you're asking for bike shed color recommendations, allow me to recommend Color.CYAN instead of the primary Blue you're using (along with rgba : [0, 255, 255, 25.5] for polygons). Generally, cyan survives poor-quality video links better than dark blue, and I find it easier on the eyes.

mramato · 2013-06-24T14:55:59Z

It's not bike shedding for things that actually matter. I'll try out CYAN. What about the opacity of the polygons? Does that look good to you (too opaque or too translucent?)

emackey · 2013-06-24T15:07:00Z

The opacity looks good. I don't think the casual observer will find a difference between 25 and 25.5, if you want to trim two bytes 😉

mramato · 2013-06-24T15:45:40Z

Okay, those changes are in. Are we happy with just using a Point primitive for points? Should we use a fancy placemark-like billboard instead?

shunter · 2013-06-24T15:56:06Z

Apps/CesiumViewer/CesiumViewer.js

@@ -50,6 +52,10 @@ define([
        window.alert(e);
    });

+    function endsWith(str, suffix) {
+        return str.indexOf(suffix, -suffix.length) !== -1;


indexOf doesn't take a negative argument. From the ES5 spec, start is min(max(pos, 0), len), which means that passing -suffix.length is equivalent to passing 0.

MDN lied to me, which is where I was looking. But you are correct. I double-checked the official spec PDF just to be sure. I'll undo my previous changes.

emackey · 2013-06-24T16:02:55Z

The default point is fine, people can configure it. Taking a second look at the OSM globe, it's very cyan already. Let's switch to Color.YELLOW (255, 255, 0). Sorry for changing my mind after you coded it.

mramato · 2013-06-24T16:12:58Z

@emackey I made it yellow, and I agree it's the most clear. That being said, keep in mind that anyone using Cesium Viewer will get these default values. I think we need a set of good looking defaults for Cesium Viewer (and I don't know why these wouldn't match the general defaults). That's why I think a custom placemark and easy on the eyes coloring is important. Yellow is visible, but not very pretty.

emackey · 2013-06-24T16:46:29Z

Yeah, the goal of a default color is just to be visible-by-default in as many different situations as possible. You can't really change your defaults based on which imagery layer is selected etc, but you can make educated guesses that the OSM layer might be popular with GeoJSON users.

A custom placemark can be nice. The upside-down raindrop shape allows more of the target area to be seen. Would we use a raster image for this, or just code a shader?

mramato · 2013-06-24T16:58:07Z

We would just base encode a png into the source, just like we do with the Bing logo. If we go with the standard placemark change, I would also change the bitmap origin so that the botton of the placemark is the actual position in the file.

emackey · 2013-06-24T17:16:30Z

Sure, non-scalable raster images can be useful. You could also use a GLSL shader.

    float len = length(st + vec2(0.0, -2.0));
    float circle = smoothstep(0.80, 0.85, len);
    float curve = (1.0 - cos(st.t * PI * 0.5)) * 0.5 * 0.80;
    float lower = 1.0 - (1.0 - smoothstep(curve, curve + 0.05, abs(st.s))) * (1.0 - smoothstep(0.95, 1.0, abs(st.t - 1.0)));
    float inscription = smoothstep(0.30, 0.35, len);
    float val = (1.0 - circle * lower) * inscription;

    gl_FragColor = color * val;

mramato · 2013-06-24T17:36:35Z

Except we have no way to express such things in the DynamicScene layer and we'd also be burdening the video card with shading all of those things that could just easily be a single static texture.

On a related topic, I was also thinking we could incorporate the Cesium logo into the placemark somehow, like instead of a black hole in the center, have the logo.

shunter · 2013-06-24T17:48:26Z

Source/DynamicScene/GeoJsonDataSource.js

+        var crs = geoJson.crs;
+        if (typeof crs !== 'undefined') {
+            if (crs === null) {
+                throw new DeveloperError('crs is null.');


Arguably these are RuntimeErrors, not DeveloperErrors, since they're caused by data loaded at runtime.

That makes sense, I almost never use RuntimeError so it didn't even occur to me. I suppose you could argue that it's a DeveloperError when using load and a RuntimeError when using loadUrl, but then we are really splitting hairs. I'll change them to RuntimeError.

…ing.

shunter · 2013-06-24T17:55:19Z

Source/DynamicScene/GeoJsonDataSource.js

+                    throw new DeveloperError('Unknown crs name: ' + properties.name);
+                }
+
+                crsPromise = when(crsFunction, function(crsFunction) {


It's not clear to me what you're trying to do here. This looks like a no-op to me:

adapt crsFunction to make it a promise if it's not already one

when that promise resolves, make a new promise that is already resolved to the crsFunction value.

mramato · 2013-06-24T18:18:00Z

Okay, all review changes so far are in. Anything else?

emackey · 2013-06-24T18:57:22Z

Good with me 👍 @shunter please merge when ready.

shunter · 2013-06-24T19:00:26Z

Source/DynamicScene/DynamicObject.js

+        }
+        for ( var property in other) {
+            if (other.hasOwnProperty(property)) {
+                if (this.hasOwnProperty(property) && (typeof this[property] === 'undefined')) {


Why check this.hasOwnProperty(property) here? Shouldn't you merge other[property] into this regardless?

Probably. I simplified it to:

for ( var property in other) { if (other.hasOwnProperty(property)) { this[property] = defaultValue(this[property], other[property]); } }

shunter · 2013-06-24T20:04:26Z

Source/DynamicScene/GeoJsonDataSource.js

+            id = finalId;
+        }
+        var dynamicObject = dynamicObjectCollection.getOrCreateObject(id);
+        dynamicObject.geoJson = geojson;


Probably worth being consistent between geoJson and geojson throughout.

1. GeoJSON is the format name. 2. geojson is the extension we use. 3. geoJson is the identifier casing.

shunter · 2013-06-24T20:14:03Z

Source/DynamicScene/GeoJsonDataSource.js

+        var dynamicObject = createObject(geojson, dataSource._dynamicObjectCollection);
+
+        var coordinates = geometry.coordinates;
+        var positions = new Array(coordinates.length);


Worth factoring out this function to convert an array of coordinates to an array of positions?

mramato · 2013-06-24T20:54:03Z

Okay, I think we're close. Anything else?

shunter · 2013-06-24T21:17:56Z

Looks good, merging.

GeoJSON support

mramato added 18 commits June 18, 2013 15:29

Start messing around with GeoJSON support.

885a6ec

Merge branch 'master' into geojson

d709321

Add drag and drop for .geojson files.

5ef9066

Merge branch 'master' into geojson

a08508a

Apply default styles to all GeoJSON features.

5bcd722

Ongoing GeoJSON prototyping.

e11f9ec

Merge branch 'master' into geojson

ff0d14d

Start of some specs, still a ton of work to do.

7c4dc49

Ongoing GeoJSON work.

bc36784

Merge branch 'master' into geojson

db085c9

Ongoing GeoJSON work.

485985e

Fix failing tests.

83fdd2f

Temporarily remove StaticProperty/StaticPosition property.

b611ffd

Have GeoJsonDataSource use private versions of them instead until I do them "for real".

More cleanup before pull request.

ae572be

Doc cleanup.

a0eb4e8

Merge branch 'master' into geojson

ddfacdc

Update CHANGES

08f5258

Merge branch 'master' into geojson

3e3188b

emackey reviewed Jun 24, 2013
View reviewed changes

Merge branch 'master' into geojson

7eca3c8

Changes after review.

67112b6