Image stretching / fuzziness in ArcGIS Explorer 1500?

danan

During a pilot we had reports of the maps being ???fuzzy??? in ArcGIS Explorer. While recording SOAP traffic for load testing from ArcGIS Explorer and ArcMap, we noticed that ArcGIS Explorer retrieves images from a dynamic map service at a smaller scale than what is being displayed while ArcMap retrieves images at the exact scale as what is being displayed.

This behavior is causing the images displayed by ArcGIS Explorer to appear fuzzy (due to stretching the image) relative to what is displayed in ArcMap.

We are using ArcGIS Explorer with:
1. 2D mode using a 2D service
2. Map properties configured with the Coordinate system set to: NAD_1983_StatePlan_North_Carolina_FIPS_3200_Feet
3. No Transformations are in effect
4. No base map (base map was cleared prior to saving the NMF)
5. Using a NC County Boundary Layer (or any other dynamic map)
6. The behavior is exhibited on initial open or on Zoom to Layer
7. The behavior is also exhibited using a fixed zoom. e.g. on zoom to city.

We have not verified if the behavior exacerbates the stretching of a cached map image. e.g. If AGX is zoomed to the exact or nearly to the exact cached scale, does AGX actually retrieve the next smaller scale?

Is this stretching in AGX by design? If so, why? Is cartographic quality being sacrificed at the expense of perceived performance gains? If stretching in AGX is not by design, is it in the pipeline to be fixed?

Another thing we've noticed:

A single pan or zoom against a map service in ArcMap typically generates a single image while single pan or zoom against a map service in AGX typically generates multiple images--seemingly including adjacent extents and scales. Can anyone else confirm that's what's happening?

The "why", I'd imagine, is to enhance perceived performance for a single user (e.g. it's highly likely that a user zoomed into a specific area will, as a next action, want to examine adjacent areas. However, this seems like it could cause total performance to degrade on a system with many concurrent users. In other words, 1,000 users accessing a dynamic map service via ArcMap are likely to load the system less than 1,000 users accessing a dynamic map service via ArcGIS Explorer. Does that sound plausible? Perhaps it's a wash given how long it takes AGX to render tiles vs. ArcMap.

danan

A few more details:

* By fuzziness, I do not mean AGX 1500's "progressive display" (aka 'crisping') where the map product comes into focus over time; but rather the quality of fully rendered static displays of vector data.

* The single image ArcMap retrieves from the dynamic map service has a dimension of 1023 x 779 pixels and seemingly displays at those dimensions (or close enough so there's no evident degradation of image quality).

* The multiple images AGX retrieves from the same dynamic map service (13 images for a single zoom operation) each have a dimension of 512 x 512 pixels.

Attached are two images both generated from the same dynamic map service:

* ArcMapDisplay1.png: shows an ArcMap 9.3.1 display. Compared with its source image, it does not appear to be stretched beyond its native dimensions.

* AgxDisplay1.png: shows an ArcGIS Explorer 1500 display of the same AOI. Compared with the source image(s), it is clearly stretched and displayed beyond its native dimensions.

So there's quite a difference in display quality between AGX 1500 and ArcMap 9.3.1. Is this an oversight or intentional?

AgxDisplay1.png

ArcMapDisplay1.png