Add rain/radar image

[smalers]

Steve is going to discuss with Catherine first.

It would be good to add support for rain/radar, in particular for the following, used at TriLynx. This would allow the InfoMapper to provide weather information.

"https://tilecache.rainviewer.com/v2/radar/{timestamp}/256/{z}/{x}/{y}/5/1_1.png", "class": "data-layer-png-rainviewer", "opacity": ".4", "loop": true, "maxImages": 10, "refresh": true },
"https://tilecache.rainviewer.com/v2/radar/{timestamp}/256/{z}/{x}/{y}/5/1_1.png", "class": "data-layer-png-rainviewer", "opacity": ".4", "refresh": true }

Technical issues include the following and it may require resolving multiple issues to fully resolve this issue.

1. Ensuring that a web map service (WMS) can be added in other than background layer group, since this will overlay the background layer that is selected.
2. Get a snapshot working first. Refreshing the map will redraw the layer.
3. If a loop viewer is used, how is that done. Talk to Catherine. Need to evaluate the approach once more is understood. For example, a looping class may replay several snapshot images and then move them forward over time.
4. This issue relates to enabling the layer refresh feature, which is a fundamental but also potentially larger issue to resolve.

[smalers]

I understand that the radar image is actually a tile server, which makes sense.

We still need a way to show georeferenced images. The following is an example of a georeferenced image of an old scanned map for Denver. Maybe source images for some maps can be obtained for testing.

https://rumsey.geogarage.com/maps/g4841001.html

See also the Water Resources Archive at CSU.

[Nightsphere]

Image Layer

The following are the currently used properties from the map configuration file.

• The geoLayerSymbol legendImagePath property tells the legend where the image for the legend lives, and let's the Map Component know that an image layer is being displayed. For now this must be the absolute path to the image, e.g. assets/app/img/denver-legend.png. It must also be no larger than 350px wide and 180px high.
• The geoLayerView property imageBounds is a list- or array-like string with 2 sets of latitude and longitude, used by the Leaflet imageOverlay constructor for positioning an image on the map. For example,

  "imageBounds": "39.784503, -105.066773, 39.714058, -104.939362"

  will display a map over most of downtown Denver.

• The geoLayerSymbol opacity property is the only other used property, used for setting image opacity on the map. It is optional, with the default being 1.0.
• The image layer refresh should be working as well. The geoLayerView refreshInterval & refreshOffset properties will work in the same way as other layers: Interval being how much time before the next refresh, and offset how much time since the previous midnight before the first refresh. The default value for no offset given is 0 (midnight).