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I'm sorry, but I can't reproduce your error. Map Tips show the value of the GPI geostatistical layer when I hover over the map.
Please contact support services. They should be able to help you resolve this issue.
Well, the Maptips are now working. What seems to have been stopping them is apparent inconsistency in extent definitions. By clicking various settings by trial and error, I got the "visible extent" and the "full extent" to match. Then I got the Maptips. I still cannot make complete sense of the Help and the explanation phrases with the choices concerning setting the extents on the GPI layer. What really seems most strange, though, and what I don't understand, is that these "mismatched" extents seem to have no effect on the contour lines (whether filled or not). These contour lines are an obvious match for the actual tract data in gradual color and don't change when I change the "extents". I don't even understand yet how the "extents" got "mismatched". Does anybody have an idea why this great difference in behavior occurs?
Eric, I would assume that you could reproduce my effect by manipulating the extents so they do not match. I need to better understand the setting and use of extents.
Even after changing the extent of the GPI layer, Map Tips still works for me. Are you using ArcGIS 10?
The default extent of any geostatistical layer is the rectangular extent of the input points. However, you should think of a geostatistical layer as a function, rather than a final result. It doesn't "know" its own values like a raster does. To find the value at some (x,y) location, the layer has to calculate the result, whereas a raster has a saved value for each cell. The geostatistical layer draws rough contour lines by making the fewest predictions it can to draw roughly accurate contours (this is why the surface often looks different after exporting to raster... this conversion simply entails making a prediction at the center of each raster cell).
Since the geostatistical layer is essentially a function that takes an (x,y) location and returns a predicted value, you can change the range of the (x,y) locations that it will accept. ie, you can change the visible extent of the layer. Changing the range of the x and y coordinates won't change the predicted value at any locations, so that is why the contour lines do not change when you change the extent.
Also, since the geostatistical layer does not have to store all of its values (instead, it stores a function of x,y), it essentially has infinite resolution (up to the precision of your computer); you can keep zooming in, and you will never see pixels like you will with rasters.
I can now produce repeatable, predictable results controlling where MapTips works. If I set the Visible Extent to a custom rectangle, say over some of the blank space in the data view, then MapTips works only there. This is possible since the polynomial is essentially defined everywhere. Apparently, when I first set up the GPI layer, this visible extent somehow got defined over some area with no overlap with the actual map. If this happens again, at least I'll know how to fix it.
But then I am perplexed about what the "Full Extent" box does at the bottom of the Extent tab. No matter what radio button I click ("of this layer" or "of the data frame"), when I return to this Properties tab, the "of this layer" radio button is always selected. In addition, I cannot see what affect selecting one of these buttons has. And, in addition still, the values for the "Top" and "Bottom" coordinates are reversed.
Well, I think I understand the Extent Tab now.
"Visible Extent" does not refer to nor is it connected to the visible extent of the map at all, but to the extent on or around or even off the map where you want the MapTips to be visible.
And the radio buttons and the extents that are displayed under them have no link to the "visible extent" at all. These buttons change nothing; they just provide reference information.