Horizon Simulations VFR USA Chicago for FS2002/FS2004

By Andrew Herd (29 August 2005)

orizon have established themselves as a mainstream publisher of photographic sceneries, thanks to their release of a pair of US packages - VFR Dallas Fort Worth and VFR San Francisco and Sacramento - and their stupendous VFR Netherlands, which I would rate as one of the most interesting scenery packages ever published. Thanks to their link with AirPhotoUSA, Horizon have more US sceneries in the pipeline, the first of which is available as VFR USA Chicago.

AirPhotoUSA's slogan is 'We Take Fun Seriously' and from the moment I looked at the way Horizon have packaged their photography for Flight Simulator, it is easy to believe that that is precisely what they do. VFR USA Chicago covers nearly 12,000 square miles of territory in a block extending west of the city and encompassing everything from the late lamented Meigs to tumbledown pastureland. One of the things that makes this package such great value for money is the vast area it covers - if you take off from Meigs and head west, even Flight1's fantastic PC-12 will still be flying over photoscenery many minutes after takeoff. Given that the PC-12 cruises at over 200 knots, this gives Horizon's package the edge over some of the other city photosceneries I have seen, which only cover around a third of the area.

The package comes on a single DVD, the minimum system specification being a 700 MHz PC running Windows 98 or better, at least 128 Mb of RAM and 3 Gb of hard disk space available (there is a disagreement about space requirement between the box and Horizon's website, which suggests 1.9 Gb). The long and the short of it is that any PC which can run FS2002 or FS2004 can run this scenery, because it doesn't consume any more processor cycles than the default textures do; but as always, the faster your PC, the better Flight Simulator will run. In addition to photographic scenery tiles for summer, the package adds a new mesh, custom night lighting and 'hard winter' effects - and it doesn't suppress the AutoGen, key elements of which have been repositioned to match up to the new landscape. A key point is that unlike most other photographic scenery packages, VFR Chicago does not install spring and fall textures by default during installation and it is necessary to run a separate application to generate them; if this is not done, featureless gray textures will appear instead of landscape tiles in those seasons.

It pays to sit near the PC during the installation, as the software installs in five chunks. Putting the DVD in the drive triggers the first stage, which was followed by a pause just long enough for me to think the software had been copied in its entirety. Just as I was beginning to wonder if the routine had fallen over, the next phase began, which ran for a while and then shut down... followed by another long pause... and then the next stage and so on, until VFR USA Chicago was done. In between each stage of the installation there is no hint that anything is happening, apart from some hard disk activity, and I am willing to bet that Horizon get regular support calls from users who think the process has finished when it is only half way through and pull the disk out the drive. It would be better if there was some kind of background graphic to let the user know something was happening, even when it looks like nothing is, because the pauses are long even on a 3.0 Ghz PC with a fast DVD.

With the scenery installed, loading times are noticeably longer, with Flight Simulator pausing at around the 54% mark and crawling for the next few percentage points, before speeding up again and loading as normal. I did many flights over the scenery, but the one on which the screenshots were taken was made from Meigs on an August day with real weather enabled. As it happened, it turned out to be a particularly good day to do the shots, because the weather closed in initially as I flew west and provided a variety of lighting conditions. I haven't included any shots of the night lighting provided with the scenery, but it looked good to me and is many times better than the default night scenery.

Photosceneries work by replacing the default Flight Simulator ground textures with new tiles painted with aerial or satellite photographs. Flight Simulator displays these with a resolution of 4.75 meters per pixel and provides a system for locking each tile in its correct geographical position, so with a bit of image manipulation and some clever programming it is possible to provide a remarkably real simulation of a particular area. There are a few limitations of photosceneries to bear in mind. The first is that the closer you get to the ground, the worse photosceneries get as the coarse resolution Flight Simulator enforces on developers becomes apparent - above 2500 to 3000 feet, the 'grain' of the tiles isn't so visible and at 5000 feet or above the landscape looks really good. The next problem is that Flight Simulator only shuffles the tiles into place when it finds time to do so, which is often a little later than you would wish, the resultant effect being that the ground only finally comes into sharp focus as you near it - but now and again, particularly if you fly faster than 200-250 knots, the terrain engine loses its place and everything blurs badly. I have been sent all sorts of tips for curing this, but the prevention works best (fly slower and don't make so many turns), reducing visibility below 20 nautical miles helps, and if all else fails, hit the pause key and wait for Flight Simulator to sort it all out. Another caveat is that because the new textures are based on photographs and take up swathes of hard disk space, you usually only get a phototextures representative of a summer season and finally, if you like running FS with the extended terrain textures option checked, you had better be a patient person, as load times extend more than somewhat.

Why does anyone buy photosceneries if they have all those problems? The answer lies in the screenshots - it looks real, it feels real, you can fly VFR with the correct sectional, and it is serious fun doing virtual tours of places you would never normally get to see from the air. These photosceneries are good enough for flying schools to use them for training purposes and once you have seen all the shots, you will understand why.

As I remarked earlier, the extent of the scenery means you can fly a long way west of Meigs, the photographic tiles covering a roughly rectangular area with its eastern edge wrapped around the south-eastern shore of the lake. Horizon's image processing is absolutely first class and their textures are as good as anything I have ever seen - having reviewed most of the photosceneries out there I have come to realise that you can't take an aerial photo and turn it into something that looks good in Flight Simulator just like that. Different developers have their own ways of doing things, the result being that each set of packages has a definite 'look', but before it is possible to comment on a photoscenery's overall quality, it is necessary to see it at as many different times of day and in as many different weather situations as possible, because the colors are strongly influenced by Flight Simulator's light engine. Before photoscenery became mainstream, I used to think the FS light engine was about as good as it needed to be, but after you I had gotten used to watching landscape completely change their hue because of minor changes in the weather, I have changed my mind. As you can see from the screenshots, this effect is somewhat more pronounced than it is in real life, though to be fair, you get used to it after a while and the benefit of being able to fly over a real looking landscape far outweighs the interesting things that Flight Simulator's light sources sometimes try to do to it.

To get the best from VFR USA Chicago you will need the sectional, which can be got from Sporty's for only a few dollars (Or download freeware images of the Chicago sectional chart or the Chicago terminal area chart.) Armed with that, all you have to do is spread the chart on your desk and start following roads. Or golf courses. About midway through the review, I began to realise that the inhabitants of Chicago have a serious problem with golf, there being so many courses scattered around the scenery that it is almost impossible to take a screenshot which doesn't include one. I find the whole deal profoundly worrying; what is it about Chicago and golf? Don't they fool around with Flight Simulator all day long like normal people? We should be told.

The immense acreage covered by the scenery means that you get to see the landscape change a good deal before you run off the edge and onto the default tiles, which makes the inevitable let-down easier to handle. Packages covering smaller areas necessarily only have a few minutes' flying between the outer city tiles and the great default FS beyond, which means that your ability to make sight-seeing flights without sight of an edge is severely limited. The shots above neatly demonstrate the many different types of terrain to be found in VFR USA Chicago, with farmland beginning to appear as the PC12 flies beyond the city limits. There are quite a few lakes in the scenery - if you run the 'Water Options' utility found in the Horizon Simulations group on the program menu you can change their state between landable/interactive and unlandable/photographic.

Going back to the flight, as I approached Du Page (left above), the vis began to clamp down and the light went with it - if you compare the three screenshots above with the two top rows, you will see how dramatically Flight Simulator's lighting affects terrain color. Unlike real landscapes, whose appearance depends on reflected color, sceneries are at the mercy of the FS lighting engine, which isn't sophisticated enough to allow variations of light across the visible landscape - the result being that you either have one type of lighting in FS or another, with quite sharp changes in between. For some reason this isn't particularly noticeable with the default tiles, but as I remarked just now, it can be an issue for some people with photosceneries, which tend to look more natural in the flatter light which Flight Simulator generates in overcast conditions than they do in bright virtual sunshine.

Hidden away in the start menu group is a 'Seasons' app, which isn't exactly highlighted in the manual, but which must be run if you want to see anything other than featureless gray textures in spring and fall. There are two flavors of this app, one for NTFS and one for FAT32 file systems - according to the manual it isn't possible to run the FAT32 version on an NTFS partition and vice versa, so if you don't know which file system you are using (most modern systems use NTFS), it is safe to experiment. My 3.0 GHz Pentium runs Windows XP using NTFS and the process took quite a while to complete. The reason why the Seasons app has to be run is complicated, but the scenery configuration files (known as BGLs, because of their file extension) used to position photographic textures contain information on which seasons are available and if they say that a particular season is available but the textures for it are not present, then gray scenery will be displayed. Historically, developers have gotten around this problem by releasing a single set of non-seasonal BGLs, or by changing the hue and saturation of the summer textures on the fly during installation, but Horizon have chosen to use sophisticated texture based night lighting which can only be provided if seasons are included in the BGLs. This led to an immediate problem, which was that if each scenery tile had been provided with four scenery textures for each of the seasons plus a night lighting texture, the distribution would have had to be quadrupled in size from 1.8 Gb to 7.2 Gb, so in order to keep installation size down, a 'hard' winter season was provided to reflect the huge snow falls Chicago receives, leaving the spring and autumn textures to be created by the user after installation, hence the need to use the Seasons app.

Once the Seasons applet has been run it allows NTFS file systems to have real photographic scenery in spring, summer and autumn as well as night lighting and the hard winter texture - occupying roughly half the amount of hard disk space they would if 'conventional' methods of providing four season textures had been used. The explanation is that Seasons NTFS fools the computer into thinking that the Spring and Fall texture sets are there by using file system hotlinks to redirect the scenery engine to the summer texture, which is why the scenery can be seen in all seasons with no additional disk space having been used once the app has been run. The reason the seasons look different is because Flight Simulator makes changes to the hue and colour of the ground tiles according to the time of day and year.

The saving grace of all this is that running Seasons NTFS only has to be done one time. Unfortunately, the FAT32 file system does not support hotlinks so a different version of the Seasons app has had to be provided which copies the Summer textures to create the Spring and Fall seasons, which it does by renaming the existing default summer textures to match those of the chosen season. The kicker is that Seasons FAT32 does not create new textures - all it does is to rename the existing ones, so FS must be quit, Seasons run and FS restarted again every time you want to change season - not great if you haven't flown into Chicago for a while and make your descent through thick cloud cover after an epic three hour flight only to discover you forgot to run Seasons FAT32 before you left and everything has gone gray. The reason the scenery behaves like this being that FAT32 has a finite limit to the number of files it can store in one folder (around 15,000 if you are interested) and creating additional seasonal textures for VFR USA Chicago on FAT32 partitions would bust this limit.

By going with seasonal textures, Horizon have made a decision which benefits the majority of potential buyers by bringing them the highest possible quality visuals in the least possible space, but FAT32 users are left with a kludge that they may not like too much. So... Horizon have provided a set of non-seasonal BGL files which can be substituted for the seasonal ones on FAT32 partitions and allow you to see the same photoscenery regardless of which season is selected in FS - which is how most other photo sceneries get around the problem. There is a section telling you how to do this in a readme in the Chicago program group, the process being pretty simple as long as you are a reasonably proficient Windows user. The price you pay for using Chicago's non-seasonal textures is that you don't get night lighting, so if you fly a lot of nights and use FAT32, you have some thinking to do here.

Moving on - hey, what's that? It's an edge. Yep, you fly over endless miles of farmland and then you come to the sight all photoscenery users learn to dread - the line where nirvana stops and Microsoft's alternative reality begins. I have included the shot on the right above partly to illustrate how this looks and partly to show how well Flight1's Ultimate Terrain USA's roads line up with the ones in the VFR Chicago package. Roads in the default FS scenery are few and far between and often well out of position, so that when they do line up it is only by chance, which makes edges much more noticeable, but whatever other packages you might have installed, the edge effect is a fact of life for photosceneries like this and it is hard to see how it can be avoided. One way around the problem would be to create 'blending' textures around the edge of the photo tiles, but this would be something like hard work, given that so many complete sets would need to be created - for each season and for night lighting. The other problem is that the blended textures would only work with the default texture set and users of replacment textures sets would be left in the cold, but I can't think of any other solutions.

Verdict? A great package, with the minor caveat that Windows newbies may baulk at the idea of having to delve into the folder structure to copy around files if they want to run the non-seasonal textures. This aside, you get an vast amount of territory for your money and the sophisticated way Horizon have processed the images makes the phototextures look a million dollars - you won't see anything that looks better than this. Given that there are nearly two hundred airfields within the area covered by the scenery, you could fly for a long, long time before you exhausted the alternatives offered by VFR USA Chicago.