Unlike many flight simulators, Tacview does not try to project a spherical terrain on a flat surface. Instead, it uses a true spherical earth. Like Google Earth, Tacview is able to display the earth in its whole like it is in real life.
That way of managing and displaying earth offers the following advantages:
However, this way of doing things has some limitations:
Tacview uses three kinds of terrains:
Below, the first screenshot shows you the ETOPO2 worldwide map displayed in Tacview. Thanks to several optimizations this worldwide base map takes only 20 MB of memory. As you can see, it is a pretty good approximation of the earth surface.
The second screenshot shows the same sector based on SRTM3 data (about 75 m resolution). This is a really high definition map. Obviously, since SRTM3 terrain represent about 10 GB of compressed data, Tacview includes only the main areas covered by our favorite flight simulators.
The last screenshot shows Flaming Cliffs map exported and converted into SRTM3 format. In average it is less accurate than SRTM3 terrain. However, since Flaming Cliffs terrain differ from the reality, it is more appropriate to display its map while reviewing flight recordings from Flaming Cliffs and Black Shark.
When no other map is available Tacview display the ETOPO2 worldwide base map. Otherwise it displays SRTM3 terrain or flight simulators terrains depending of their availability and user preferences. At anytime, the user can switch between terrains thanks the option [Settings|Terrain].
The following tutorial explains how to add new terrains to Tacview. This works with any version of Tacview. Note that upgrading existing terrain works the same way: You just have to add your terrain and Tacview will use them instead of those provided by default.
In this tutorial, we are going to add the high definition map of Corsica into Tacview.
First, we must check boundaries of the Corsica terrain. Since SRTM3 sectors are 1 by 1 degree each, we have to round boundaries to 1 degree. According to Google Earth, Corsica boundaries are: from N41° E8° to N43° E9°.
Then we have to download corresponding SRTM3 sectors from the NASA server. Those data are free for use by anyone for any purpose! So let's download our 3x2=6 sectors:
Then we have to unpack those data and put them under the proper folder. There are two types of SRTM3 terrain which can be customized by the user:
Since our data is from real life, we are going to put it under the SRTM3 folder. We just have to create the proper sub folders where Tacview is installed and put our unpacked data into it.
That's it! We can now see in Tacview our brand new high resolution Corsica terrain! (See the screenshots bellow)
However, we can notice holes in our map. Because of clouds, atmospheric perturbations and trees, the shuttle radar was not able to pick all details. This is why we have missing data, especially in mountains.
Here how we are going to fix that:
First, we should have a look at Jonathan de Ferranti web site. Jonathan has already cleaned many SRTM3 sectors. Since he used other real-life data to fix those holes, if we can find Corsica Mountains on his web site, we are going to have pretty accurate SRTM3 data.
Here we are: Let's download his Corsica n42e008 sector! Unpack it and replace our original file by this one. As you can see this is a huge improvement over original defective data.
But we still have many tiny holes remaining almost anywhere else!
Now we are going to use a program to fix those holes thanks to mathematical algorithms. Obviously this is not going to be as accurate as Jonathan work but that will do the job pretty well, especially with our tiny holes.
Blackart is an 'interesting' program: It is painful to use and it crashes all the time... However it is really good at fixing SRTM3 data. As you are going to see, it gives really great results:
Since we selected high quality settings, sectors cleanup will take a lot of time (usually about 1 minute per sector on a 2008 computer). We have to wait until Blackart has completed his work or until he has crashed. Be patient and don't worry. Original files are not going to be modified, Blackart create new files suffixed hgx. So you just have to restart the process from where he has crashed.
After this painful (but almost automatic) process we should have our 6 cleaned SRTM3 sectors ready for a new try! So, let's delete (or backup) our original hgt files and rename *.hgx files from Backart to *.hgt.
That's it! We can now launch Tacview and see our new clean high resolution landscape! The following screenshots show from left to right:
In overall the process is the same as for adding SRTM3 terrain data. Except that instead of taking data from the NASA, you will have to export and convert it from your flight simulator:
The following folders are natively supported by Tacview (however you can use any other name your want):
Depending of the simulator this is a pretty difficult task because of the following points:
Unfortunately I cannot help you in that task because every simulator is unique. However, here some documentation which may help you:
Do not hesitate to contact me if you need more information or you have any requests.
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