Last night I searched for an hour for some past threads explaining the arcs, seconds, LOD etc of terrain mesh by the gurus. I've seen them but now I can't find them again. Could someone post a link if they have one please? I was interested in this because I read about the new meshes by Lago of Europe and wanted to compare the facts. It's all very confusing?Thanks for your replies, I'll be back!Charles

Charles,I have a brief discussion of mesh quality (more coming) on my web site. While my focus has been on the USA, the discussion may help clarify some of these issues for you. www.fs-traveler.com/quality.htmlBe sure to check the link to "two-stage process" on that page The sketches emphasize the relative importance of the source data and the final LOD as they relate to the "realism" of the mesh. The limited availability of good, economical high resolution source data is problematic for areas outside the US. This is the most important factor affecting the final quality of the mesh, yet there seems to be some reluctance on the part of some mesh developers to reveal the actual resolution used, even though it must be specified as part of the construction process.The description of the Lago mesh is not very clear. This is not a comment on the quality of their product, but it is difficult to understand how they actually prepared the data. They are to be commended for providing the information, and terminology and translation are probably factors.They report using the following data sources:DTED Level 0 - elevation post spacing is 30 arc second (nominally one kilometer).VMap Level 0 - Details similar to 1:1 million-scale or 1:2 million-scale paper charts. (nominally one kilometer).VMap Level 1 - Details similar to 1:250,000-scale paper charts. (about 90-100 meter spacing)(In general, medium resolution US mesh is made from 30 meter source data, high resolution mesh is constructed from 10 meter data.)The realism of the areas constructed using Vmap level 1 will be much better than the rest, but how much of the mesh was constructed from that data is not obvious, nor what areas. Their refusal to "oversample" the data to claim higher REAL resolutions is commendable.Their "REAL" resolution probably refers to the LOD used in the conversion process: LOD8 -> 152.9m, LOD9 -> 76.4m. "Final" might be a better term. Good luck,Stevewww.fs-traveler.com

Thanks Steve for your reply and the detailed info, I am heading over to your link now for a looksee.Charles