Sign in to follow this  
Guest sgreenwood

Build Mesh Scenery using GTopo 30 data. "Waste of Time

Recommended Posts

Hi everybody,I have been searching for some good elevation scenery for South America, specifically for Colombia, Ecuador and Venezuela, but cannot find any. I am thinking about jumping into the terrabuilder stuff to try and create it using Gtopo 30 data. In your experience, is this a bad idea or a good idea. I wanted to get your opinion before I invest alot of time. Thanks for your input,Shane Lewis

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

Hi Shane.That data can give an improved looking mesh at an LOD of 7. Trying any finer mesh would result in severe oversampling... it might look nicer ( more 'bumpy' ) but it will start to escape reality. :)Hopefully, Steve Greenwood, or Justin Tyme will also reply.Dick

Share this post


Link to post
Share on other sites

Hi All, thanks for the responses. So, what am I missing? It seems that I really need some high res DEMS to do it right. Is that why it's not really been done yet? Is this info hard to come across? By using a 30m DEM, i assume this would result in severe oversampling?Thanks & Comments appreciated.Shane Lewis

Share this post


Link to post
Share on other sites

Hi Shane, Gentlemen:I did take a couple of days (some time ago) to construct mesh for the globe using GTOPO30 data (LOD7) and use it as my "base" mesh, so I may be able to help a bit.The majority of the default mesh used by MS does seem to be of somewhat lower resolution. In most areas of the world not further enhanced by MS, the GTOPO30-based mesh ranges from different to a nice, but usually not a substantial improvement. I suspect that the improvements are largely a matter of chance. Where the spacing between elevation data points is smaller for the GTOPO30 data, there is a better chance that interesting terrain features will be captured, perhaps even closer to their min/max elevations. As a result, my main impression is that there is usually more definition in the terrain.Shane, whether using this data to create mesh is worthwhile depends on your current experience with constructing mesh and how much improvement you are expecting. (You might also want to consider FSTerrain for working with this data.) There is a learning curve, but creating "mountains out of molehills" can be very satisfying.High res DEMs would make a big difference but are probably not readily available, or not in a format we can handle easily. Many of us are looking forward to the promised release of better global data collected by space shuttle.Source data resolution (30m DEM) is not related to oversampling. That term is used to describe the relationship between source and final resolutions. For example, converting 1000m GTOPO30 data to a final resolution of 38.2m means most of the final data was created mathematically and adds no additional detail, only much larger file sizes. 30m DEM -> 38.2m mesh is fine.I'll take a few screenshots and make them available tomorrow. I may still have some comparing the default mesh with mesh created from GTOPO30, 100m and 30m source data for a small mountain range in central Massachusetts. Even here in the US the GTOPO30 data can be a bit more interesting and in this case, the range is positioned more accurately than the default.Stevewww.fs-traveler.com

Share this post


Link to post
Share on other sites

I've created a page with a sample screenshot and a link to a set of screenshots that can be downloaded.You can also download "sample" mesh for NW South America, for a limited time only. There is an image at the bottom of the page showing coverage, but no installation instructions. Just unzip and copy the bgl file to your ADDON SCENERYscenery folder.www.fs-traveler.com/ss-gtopo30comp.htmlSteve

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this