Latitude Factor Calculation

Hello All,

I was told about this when I was having WMS imagery quality issues, and adding what Kevin suggested helped for the WMS side of things;

if (tilingScheme instanceof GeographicTilingScheme) {

latitudeFactor = 1.0;


So now I have started adding ArcGIS overlays, and as they aren’t part of the GeographicTilingScheme the latitudeFactor is still calculated.

Currently, this makes it look quite bad. If you go to this sandcastle [1] and paste in this js code;

Hey Toby,

I tried what you said, but it actually looks pretty reasonable to me. Can you be more specific about what you’re seeing? Having different levels of detail visible in a scene is expected, even though it can sometimes create artifacts such as cut off labels.

I didn’t try turning off the latitude factor for this ArcGIS imagery, but I did try it for Bing Maps awhile back. What I found was that it caused the imagery to be oversampled near the poles. For example, text became extremely tiny. Since this ArcGIS MapServer uses the same tiling scheme, I would expect similar behavior.


Hi Kevin,

Attached is what I am seeing - the left is from the sandcastle example, the right is my dev version with latitude factor turned to 1. And I get what you mean about the text, although for me it’s lovely and crisp… rather than too small.

I guess it depends what layers I have on. Currently just the bing aerial and an arcgis overlay layer (as mentioned)…


What about when you zoom in really close to a northern point? I suspect that the text will become too small to read at that point.

On CentralBodySurface, there’s a property ‘_maximumScreenSpaceError’. It’s set to 2. You might try changing it to 1.5 or even 1 and see if that gives you a scene more to your liking. That should sharpen up the scene all over, at a performance cost.


So setting that to 1.5 makes the Europe region look great - however anything near the equator is then too small to see.

I think I’d be more prepared to sacrifice far north labels than equatorial ones…

Also, is there a performance hit for forcing the latitudeFactor to 1?



Hmm that is surprising. This is with the latitude factor enabled I assume?

There is some performance hit to setting the latituteFactor to 1 in that it causes more textures to be used near the poles. But it shouldn’t be too terrible overall. If it’s working well for you, by all means use it.

I clearly need to spend some more time analyzing the effect of that latitude factor to figure out when (and even whether) it should be used. Thanks for keeping me informed of what you’re seeing.