Map Layer's tiles load at default alpha even when the entire layer has a lower alpha

ManishAmin · ‎10-14-2013

Hello,

If I put any map layer, Bing's VETiledLayer, ArcGISTiledMapServiceLayer, etc.. at a < 1 alpha, such as 0.75, the map tiles load at the default (1.0) alpha upon zoom in and out and then the entire map layer suddenly dampens to the layer-set alpha. This is visually unappealing and quite jarring. Panning in new tiles does not do this, they correctly load with the layer's lessened alpha.

Is there a fix or work-around for this? In addition to setting the alpha on the layer, I have also tried using an alpha filter but I get the same jarring results. I do not want the "Map" component to be alpha'd, just the "map layer".

Here is the simple setup...

<ns:Map id="map" width="100%" height="100%" ........>
<ns:ArcGISTiledMapServiceLayer ..... alpha="0.75" />

Thank you for your help!

YueWu1 · ‎10-14-2013

Hi Manish,

Which version of the Flex API did you use? (Might be try a new version of Flex API 3.5)
Also, how many layers are specifically added in your application?
You said "I do not want the "Map" component to be alpha'd, just the "map layer".
If you have more than 1 layers, the order of your map will decide the way of transparent.
Also, if you do have symbols on renderer, I would recommend to add alpha property just in case to keep their display.
For example: <esri:SimpleMarkerSymbol id="symbol5"
alpha="0.7" />

In a summery, you can change mainly 3 categories about the map alpha:
1. The TiledLayer (basemap)
2. The FeatureLayer, DynamicServerLayer and any other layers
3. The symbol on your layer

Here I post a Silverlight Layer documentation, even though its a different API, but the concept are the same, hope this can help you understand the issue.
http://resources.esri.com/help/9.3/arcgisserver/apis/silverlight/help/adding_layers.htm

ManishAmin · ‎10-15-2013

Hi, thanks for the response but I don't think you fully understood my question.

I am using the latest Flex API 3.5 with also the latest Apache Flex SDK as well as up to date Flash Player and Adobe Air runtimes.

As of right now, the number of layers on the map doesn't matter, the issue is with the TiledLayer itself. Perhaps my word usage in my original question was off. When I mentioned "Map component", i am referring to the overall master <esri:Map. .../> component. When I mentioned "map layer", I was referring to the basemap such as a <esri:TiledLayer ../> etc...

Here is the ultimate goal I am looking for:

1. Have a base map, whether it is VETiledLayer, or whatever. I'm talking about the layer that holds the actual geographic map.
2. Have Graphic Layers with various shapes and components.
3. I want to alpha the basemap VETiledLayer to 0.75 so that the underlying geographic basemap is dim so that the Graphic Layers pop out. I want that tied to a slider component so I can toggle this.

Now, I have gotten all of this working perfectly already. I have the basemap layer alphed to a dimmer 0.75 and bound to the slider.

However, when you zoom in our out, as the basemap layer gets new tiles for that zoom level, the tiles come in at a fully 1 alpha by the esri code, then when all of the tiles are in, the entire basemap layer drops down to my specified 0.75. So it basically gives a "flashing" effect which is not good. I need help with this, or perhaps let the Esri team know that this is a potential bug.

Does anyone know a way around this?

Hi Manish,

Which version of the Flex API did you use? (Might be try a new version of Flex API 3.5)
Also, how many layers are specifically added in your application?
You said "I do not want the "Map" component to be alpha'd, just the "map layer".
If you have more than 1 layers, the order of your map will decide the way of transparent.
Also, if you do have symbols on renderer, I would recommend to add alpha property just in case to keep their display.
For example: <esri:SimpleMarkerSymbol id="symbol5"
alpha="0.7" />

In a summery, you can change mainly 3 categories about the map alpha:
1. The TiledLayer (basemap)
2. The FeatureLayer, DynamicServerLayer and any other layers
3. The symbol on your layer

Here I post a Silverlight Layer documentation, even though its a different API, but the concept are the same, hope this can help you understand the issue.
http://resources.esri.com/help/9.3/arcgisserver/apis/silverlight/help/adding_layers.htm

YueWu1 · ‎10-15-2013

Hi Manish,

Thank you for your explanation about the question.
Here are another two ways better to test how much the display tolerance about flashing issue.

Firstly, check out the sample code link to compare how this map display performance when zoom in/out:
https://developers.arcgis.com/en/flex/sample-code/based-on-mapserver-layer.htm

If still not comfort with the sample performance, then it is the default API display performance.
If you comfort about the sample performance, then compared the sample code to change something difference.

Secondly, what browser are you using for viewing? I tested the map flashing issue on Chrome, Firefox and IE. Personally, I think the chrome performs the least flashing issue when zoom in/out.

Hope this tips can help you.

ManishAmin · ‎10-15-2013

I am using an AIR desktop application. However, test in web does the same flicker.

Take the exact code from the link you have me and use this line:

<esri:ArcGISTiledMapServiceLayer url="http://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer" alpha="0.25"/>

Put the alpha very low as 0.25 so you can see the flicker.

I already know it is the API that is doing it. I am wanting to know if there is a way for it to NOT do it.

Perhaps an ESRI team member has an idea for a workaround, or if they can file a bug to have it no longer happen in the next release. It would be greatly appreciated.