Ben Discoe, 2004.05.18
Test machine: 1GB RAM, WinXP, ATI Radeon 9800 w/128MB RAMI tested an evaluation version of the TerrainView standalone application, version 2.1.0.9. It is accompanied by a online manual in PDF, which i found to be excellent, clear and well illustrated. After a previous 2 hour evaluation of TerrainView 2.0, i spent an additional 4 hours running the 2.1 software.
Navigation
I found navigation to be very easy and intuitive, perhaps because the style of mouse navigation uses the very same behavior as other systems i have used, including WTK and VTP. Their navigation "module" gave an alternate and very clear way to move the camera. It's good when applications offer multiple ways to do things.
Scenery
I tried the "Switzerland" installable demo dataset. This dataset consists of an area around Lake Lucerne, with moderate resolution elevation and very attractive aerial imagery. A few points of interest were denoted with floating text labels, but otherwise there was purely elevation and imagery.
Texture data was paged in and out, which was somewhat visually distracting until i found the "Quality Factor" slider under Options. Quality has a range of 1 to 10, with 1 as the default. Increasing this factor to 2 make the texture paging significantly less visible.
Moving to a new unvisited area took around 5-20 seconds to page in the full detail from disk. While viewing this dataset at this quality level, the TerrainView application used around 256 MB of RAM.
Next, i tried the 'Reutlingen' demo dataset. This dataset contains a section of a city, with building and billboarded trees. The buildings looked attractive and realistic. The only significant issue with their appearance was that their texture maps were only displayed when very close to the viewer, otherwise appearing grey. I tried increasing the Quality factor, in case this could be addressed similarly to the issue with ground imagery, but it did not affect the building textures. I looked for but did not find an option for building LOD distance.
A nice feature of the navigation in this dataset is that the viewpoint is prevented from going through buildings. However, the viewpoint was allowed to go precisely up to the surface of the building polygons, resulting in clipping the building wall and seeing through the building. The constraint for geometry below the viewpoint worked better; it had an offset of a few meters which allowed natural walking on horizontal building geometry. This offset should probably be applied to the left and right of the viewpoint as well.
Finally, i tried the 'Hamburg' demo dataset. The buildings in Hamburg did not suffer the same cutoff for their textures as in the Reutlingen dataset. The only curious issue with Hamburg was that the scene, including ground and buildings, were myst
Interaction
Loading external 3D objects and moving them around with the mouse was quite easy and natural. The trees and buildings in the 'Reutlingen' dataset appeared to be build into the scene (although modelled separately) so they could not be selected, queried, moved or otherwise modified. The buildings in 'Hamburg', however, included individual 3D models which could be selected and moved.
Time of day is controllable smoothly with the GUI, and being able to switch between the predefined skydomes on the fly was very nice.
Recording a flight path was reasonably easy. Control flight speed on playback was interesting: by setting the travel time for the whole path, rather than setting speed directly.
More Issues
The documentation mentions that only 4 coordinate systems are supported: CH1930, WGS84, FlatGrid, and None. I found it strange that a terrain tool such as this one apparently does not include a library for support of standard cartographic coordinate reference systems. Version 2.1 reported adds support for UTM; however, the demo datasets appeared to be modelled in a local coordinate system; i was unable to figure out how to query it as UTM.
The TerrainView 3D window, when not on top, would periodically overdraw other windows. I found the workaround to this problem was to minimize the TerrainView window completely, when using any other applications at the same time. This might be a specific interaction between TerrainView, XP, and the ATI driver, although no other 3D apps on the test machine exhibited this problem.