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nudata

An explanation of the Blurries

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By request, here is a repost of this text.Long after the release of Flight Simulator X, many people continue to complain of the visual display. They are convinced that they have the "Blurries". This clearly demonstrates the confusion surrounding the problem of the dread blurries. While it has been discussed numerous times, inevitably many people have not seen all the comments or do not understand or wish to understand the problem. At the risk of belaboring the point, here is how I view this problem.As always, the following is not based on privileged information from the developers at ACES, nor am I myself a systems expert, nor qualified in any way in computer graphics. However, I have been working with the FS terrain engine for many, many years, have read the S.D.K. documentation for various versions of the game, and also the all too short technical papers available on the official Flight Simulator site. Nonetheless, I do not claim to know the truth about this in all the details, and can only hope that the broad lines are true, and that one of the ACES developers will step in and correct me where I am wrong.Many people complaining of the Blurries do not, as a matter of fact, suffer from them. So:1. What are the dread Blurries?If, for any reason, video memory cannot be filled with required textures, the game will drop the largest MIP maps so that more important textures such as those of the user aircraft and other objects can be displayed. Since the largest and most numerous textures are those of the ground, their largest MIP maps are the first to go, thereby creating the dread Blurries.The Blurries are not when patches of distant ground are not completely clear. This is not the Blurries, for example:http://forums.avsim.net/user_files/192167.jpgThe Blurries are when all the ground textures, even those directly below the user aircraft, are not clear, for example:http://forums.avsim.net/user_files/192168.jpgHow to get the Blurries: Very simple, place the aircraft close to the ground, less than 1000 ft. AGL where the largest MIP map is always displayed, and then slew as fast as possible, 1500 knots should do. Quickly, the game will not be able to catch up with the ground textures and will start to drop the largest resolution MIP maps in favor of smaller ones, giving the above result.2. What are MIP maps and what is their purpose?All the textures in FS, and probably in many other games, contain multiple images with different resolutions. For example, the maximum resolution in FS is 1024 x 1024 pixels, but the image file also contains progressively smaller versions of the same image: 512 x 512, 256 x 256, 128 x 128, etc. up to 9 different sizes of the same image.http://forums.avsim.net/user_files/192169.jpgEach of the images has a different resolution:- 1024 = 1 (1.2) meters per pixel- 512 = 2 (2.4) meters per pixel- 256 = 5 (4.78) meters per pixel- etc.Not only are the dimensions smaller, but the sizes in kilobytes as well, since 512 x 512 pixels is 1/4 the size of 1024 x 1024, 256 x 256 is 1/16th the size, etc.The game will display the smaller MIP maps as viewer distance from the object increases, since it makes more sense and is a more efficient use of resources than always displaying the largest, highest resolution image at all times, even when the object is barely visible.(This is why the very common use of non-MIP mapped textures by third-party add-ons is a serious mistake and can only increase the probability of the dread Blurries, since it is a means of trying to force the game to always use the largest texture, thereby more easily saturating memory.)3. What causes the dread Blurries?In previous versions of Flight Simulator, and Combat Flight Simulator 2, the Blurries were caused by insufficient threads allocated to terrain texture loading. The terrain team at ACES fixed this for FS X:http://forums.avsim.net/dcboard.php?az=sho...ing_type=searchNow, the problem is video memory. Right now, many are thinking, "No, that is not it, I use MemStatus and can see with my own eyes that there is plenty of memory left."If only life were so simple. Video memory does not exist in isolation, and there are other things to take into account.For example, bandwidth - if this is limited compared to the immediate needs of transferring textures, then the memory will not have the large textures and will display the lower resolution that were already present until they can be loaded.For example, memory speed. The video card is swapping unused large resolution textures that are no longer needed out of memory and swapping in those that will be needed. A small lapse can create a bottleneck leading to a sudden and short-term case of the Blurries.For example, contiguous memory. As Phil has pointed out many times, the game will require a mimimum size for the blocks of memory and if those available are not large enough, then the required textures cannot be loaded, and the result are the dread Blurries. (By the way, have you changed the default value for Bufferpools? You may yourself have created the problem by making FS look for very large pools that are sometimes not available. Something to think about.)In all cases, the problem is getting the required high resolution textures as quickly as possible into memory so that they can be displayed for the user before the Blurries manifest themselves. So, if you get the Blurries, your problem is most probably something like the above.4. How to solve the Blurries?Certainly, I do not mean to lecture anybody. FS is a computer game, do what you want. But, if the above is true, then there are different approaches to solving the problem of the Blurries.First, upgrade the hardware. Not just the video card, but also the bus, and the memory on the card. Throwing hardware at display problems has always solved them (in the short term, until developers decide to stress systems again.)Or, if you are not willing or able to do so, then turn down the requirements of the game to levels that the hardware can handle. In other words, lower slider settings.Or, you can try "tweaking", that is, a desperate search for some hidden and badly understood setting that will allow your hardware to outperform its specifications. Aside from overclocking, there is really very little that can be done in this domain, so it is often doomed to failure, or at most to very small gains.Given the above, it seems very clear most people do not suffer from the dread Blurries at all.What people see is simply the Level of Detail Radius at work. So:1. What is Level of Detail Radius?There are at least 2 major elements to this function

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Excellent report. This should lay to rest many fruitless "adjustments". There are limits.Maybe more people will realize that this is a FLIGHT simulator not Google Earth.Regards,Dick BoleyA PC, an LCD, speakers, CH yoke

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Thanks for that - I missed the original post as well and its an interesting article. I've been pushing the LoD setting upwards, so I'll try lowering it below 4.5 and see what that does.One question - is there any way of setting different LoD numbers for the texture load and display? Basically, I'm looking for a .CFG setting to tweak if its available. Taking your examples, pre-loading ground texture all the way from Paris to the English Midlands seems excessive, as it would take some time (hours) to fly there. This points to the need for a low LoD setting, but on the other hand, increasing the LoD Display setting to beyond the visible horizon would be nice - but to do this I'd need a high LoD. Bob,

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As to your question, for FSX, the two settings appear to be linked in one slider.Maybe FS11??

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Luis,I missed the first post also. Your explanation is very easy for me to understand and I appreciate technical posts that I can understand.Thank you for taking the time and trouble to write it.

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Excellent post, I saw the first one and enjoyed re-reading it as much as I did the first time."Not recommended - Some people have increased the LOD radius value in the fsx.cfg file to higher levels; I have even seen recommendations of 8.5. "For those of us that like to tweak, what is the default setting for LOD radius? Or maybe I should ask what is an achievable setting (obviously a setting of 8.5 is asking for trouble).Thanks, Bruce.

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The setting for "High" is equivalent to LOD radius = 4.5This is the maximum option that can be set in FSX, using the Settings Menu.

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I read through the original thread. Today while flying an approach into KMSP Minneapolis, I noticed texture away from my plane were partially loaded, but the ones right near my wings were very blurry. What is this called?I was flying a straight line for about 5 miles at around 120 ktsblurreswtf.jpg

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Hello Ryan,I would call this... the dread Blurries. A mild case, though.As mentioned above, the problem is getting the required high resolution textures as quickly as possible into memory so that they can be displayed for the user before the Blurries manifest themselves.So, we could assume that somehow those textures are being held up. Some possible reasons for that:1. From your screenshot, it seems that you are running some scenery package that adds roads and textures underneath them. Perhaps these extra textures are creating a bottleneck of some kind.2. If you are using an aircraft with many high resolution textures, and if you have cycled the views (2d cockpit, 3d VC, outside views), then you have loaded all those textures. The aircraft textures have priority and will not be purged from the cache unless absolutely necessary, so they could be taking up too much memory and not allowing timely loading of ground textures.3. If you are using high resolution clouds, environment textures, or others, then they could also be part of the problem.4. The default aircraft traffic file uses the default aircraft that all have many high resolution textures, thereby more easily leading to the Blurries.5. Any other reason that you can imagine concerning high resolution textures.The solution is as mentioned above - reduce the texture load. For example, you can try disabling the roads or the textures under them and then fly again. See if you can reproduce the problem.Or, do not cycle the views, and always remain in the cockpit without loading the outside view.Or, remove any other high resolution package that you are using.Or, alternatively, re-size your textures to smaller sizes (there are numerous packages in the Avsim library that already do this for default objects and autogen trees and buildings.)Good luck.Best regards.Luis

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Hey sounds like everything I run lol!Ultimate Terrain X USAFlight Env X Super Hi-def cloudsthe plane was Tim Conrad's Mooney Mite with dds texturesMainly I'm guessing my system is simply overwhelmed?When you write "disable roads or textures under them" what do you mean by textures under them?

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UTX config tool has an option for Urban road encasement and Rural road encasement. This is the green texture that the freeways are placed over.scott s..

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Luis, many thanks to you for putting this information in a very easy to follow dissertation. I had an intuitive sense of it, and this confirms my own guess about what is happening.Again, thanks and that was spot on.Noel

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