CRS:84 not equals EPSG:4326

CesiumJS
1

Hi all.
Why Cesium not change axis ordering on WMS 1.3.0 on switch CRS from CRS:84 to EPSG:4326 ?

Example EPSG:4326 BBOX=0,90,90,180
https://sergeserver.noip.me/integration/wms?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&FORMAT=image%2Fpng&TRANSPARENT=true&LAYERS=Global%20vector%20coverage%3ALAYER0&TILED=true&WIDTH=256&HEIGHT=256&CRS=EPSG%3A4326&STYLES=&BBOX=0%2C90%2C90%2C180
Example CRS:84 BBOX=90,0,180,90
https://sergeserver.noip.me/integration/wms?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&FORMAT=image%2Fpng&TRANSPARENT=true&LAYERS=Global%20vector%20coverage%3ALAYER0&TILED=true&WIDTH=256&HEIGHT=256&CRS=CRS%3A84&STYLES=&BBOX=90%2C0%2C180%2C90

maybe I'm wrong ?
What happen if I change crs to EPSG:4326:

Correct example in CRS:84:

2

Cesium currently only supports only supports web mercator and WGS84, so you might have to reproject your data before loading it into Cesium. See the discussion on that here (https://github.com/AnalyticalGraphicsInc/cesium/issues/3877).

Although there is a PR open that might be adding support for more projections:

https://github.com/AnalyticalGraphicsInc/cesium/pull/7438

3

Both CRS:84 and EPSG:4326 is WGS84. Deference from CRS:84 and EPSG:4326 is axis ordering lon/lat or lat/lon
Look to WebMapServiceImageryProvider constructor:
        // Use SRS or CRS based on the WMS version.
        parameters.bbox = '{westProjected},{southProjected},{eastProjected},{northProjected}';
        parameters.width = '{width}';
        parameters.height = '{height}';
        if (parseFloat(resource.queryParameters.version) >= 1.3) {
            // Use CRS with 1.3.0 and going forward.
            // For GeographicTilingScheme, use CRS:84 vice EPSG:4326 to specify lon, lat (x, y) ordering for
            // bbox requests.
            parameters.crs = defaultValue(options.crs, options.tilingScheme && options.tilingScheme.projection instanceof WebMercatorProjection ? 'EPSG:3857' : 'CRS:84');
        } else {
            // SRS for WMS 1.1.0 or 1.1.1.
            parameters.srs = defaultValue(options.srs, options.tilingScheme && options.tilingScheme.projection instanceof WebMercatorProjection ? 'EPSG:3857' : 'EPSG:4326');
        }
In WMS 1.3.0 we can use EPSG:4326, but axis ordering hardcoded in code.
For EPSG:4326 in WMS 1.3.0 must be invert axis ordering. Example:
        if (parseFloat(resource.queryParameters.version) >= 1.3) {
            // Use CRS with 1.3.0 and going forward.
            // For GeographicTilingScheme, use CRS:84 vice EPSG:4326 to specify lon, lat (x, y) ordering for
            // bbox requests.
            parameters.crs = defaultValue(options.crs, options.tilingScheme && options.tilingScheme.projection instanceof WebMercatorProjection ? 'EPSG:3857' : 'CRS:84');

            if (parameters.crs === 'EPSG:4326') {
                // Change axis ordering
                parameters.bbox = '{southProjected},{westProjected},{northProjected},{eastProjected}';
            }
        } else {
            ...
        }

In local repo I fixed this, and work fine. However, I want the changes to be made in main stream repository

4

Oh, thanks for the clarification and posting the fix! We’d absolutely appreciate a pull request to add this fix into Cesium. Check out the contributors guide:

https://github.com/AnalyticalGraphicsInc/cesium/blob/master/CONTRIBUTING.md#pull-request-guidelines

Let me know if you have any questions.