Flight Map Clarity--Map Zoom Level vs Mesh Resolution Level Explained for FS2004

Have you ever opened up the flight map in FS2004, and as you've zoomed in and out, wondered why sometimes the topography (terrain) depicted in a specific area appears clearer at some zoom levels than others? Or why at one zoom level it appears clearer in some areas than others? Well the answer is that there is a direct correlation between focus/clarity in the flight map, and the resolution of the terrain mesh installed in the simulator for that geographic area. In other words, one can use the flight map in FS2004 (World/Map in the simulator pull down menu), to tell which level/resolution of terrain mesh is present in the area within view of the map.

My Primary Motivation:

So why was I motivated to pursue this, you might ask? Well, when I first got FS2004 and loaded the discs into my computer, I (like probably a lot of people) relied upon the flight map to figure out where I was going, as well as to quickly spot-move my plane to various locations. As I zoomed in to get a closer look at where I was, I couldn't help but notice that the terrain image on the flight map got very blurry, to the point where it was almost of no value at all. I attributed this to a limitation on the flight map itself, but so long as the airport labels were legible, I gave it very little thought after that.

Then last year I began including add-on terrain mesh with a higher resolution than the stock terrain mesh that came with the install discs. Originally my greatest concern was how this had improved terrain once flying in the simulator itself, but I also discovered an unintended consequence when I opened the flight map to have a look at the areas where I added the new mesh. I thought to myself, "Hmm... that's odd. I don't remember the terrain in the map image being so clear at this map zoom-level before." And that's when it hit me like a ton of bricks: The new terrain mesh was actually affecting how the flight map topography focused at different zoom-levels.

My next thought was that there had to be a way to quantify this discovery so that it didn't seem so random and haphazard when I attempted to explain it to others. So after installing various levels of mesh in different areas, and testing various zoom-levels on the flight map to compare with them, I started to find consistencies that made sense. That's when I compiled the data for my spread sheet chart, the whole concept came together, and I became really excited about sharing it with others. I have found this helpful in determining which add-on mesh products I might want to include in given areas that are missing them, and I hope others will find this information beneficial as well.

Before I continue, I ought to mention three things:

1. 'tmfviewer.exe' (located within the TERRAIN_SDK\Terrain_Tools folder) is a good program for opening up terrain mesh scenery, and having a good look at the geographic area that each .bgl file includes. Unfortunately though, it provides no information on the "Resolution" (expressed in meters) or "Level of Detail" (LOD) of the file in question. This is the main reason why my method and this article is of relevance.

2. A helpful reference guide that lists all the default scenery in FS2004 by file name, resolution, and location; I have included below in the appendix of this piece. This was originally provided courtesy of Mr. Steve Greenwood, and thank you to forum member "StringBean" for providing access to the list, in his reply to a forum post of mine on September 3, 2011.

3. Except for special circumstances, one can assume that the majority of the world's highest base default mesh is done at LOD 5 (1223m). The prime exceptions to this are the United States at LOD 6 (612m) and Australia at LOD 7 (306m). The others can be found in the chart I mentioned above in #2.

Flight Map Controls:

Upon opening the flight map, the map will always start at what I call the "default-zoom" or "neutral-position". From there, you can either zoom-in with the "+" key or zoom-out with the "-" key. There are 6 mouse clicks from neutral in both the zoom-in (+) and zoom-out (-) directions. Upon reaching the 6th click in either direction, the chosen zoom button will gray out, meaning you can't go any further. It has been my experience that once you've hit the 6th click, it is best not to count back the other way to try to get yourself back to neutral. The count messes up and it will be off 1 or 2 clicks from what it was on the way out. Rather, in this case it's better to either exit the map and come back in, or hit the "plane centering" button to the right of the zoom buttons, which will automatically center your plane in the "default-zoom" position:

As you zoom in and out various levels on the map in a given location, you will notice that the topography depicted in the flight map varies in focal quality, appearing sharp in some cases, while blurry in others, even within the same zoom level. Whichever zoom level brings the map topography in focus, will tell you which level of mesh terrain is installed in that area.

Now certainly more than one level of mesh may be installed in a certain area, be it default from the original FS discs, or an add-on that you may have installed yourself. It is entirely possible to install all the levels of mesh in a given area so that nearly every mouse click you zoom in or out, the map topography will almost always be focused. I say "almost" because there are some exceptions that I have noted. This would be the best case scenario...if one wants to take the time to download and install all that mesh (assuming all of it is even available for every square mile of the globe).

It is also important to note that even if one runs only default terrain straight off the discs, that terrain resolution can vary greatly, especially in areas of special interest where Microsoft presumably wanted to highlight the detail. It may not be so important to note which terrain mesh level is present, as it is to determine which terrain mesh level is missing!