Four points about FSX and Blurries

First and before I forget - Happy New Year!

 

Next, this post is not meant to minimize, marginalize, or denigrate anyone who has the blurries. This post is meant to discuss the data I have in front of me as a result of investigations on this topic. Please do not take this information in the wrong way and see it as an attempt to minimize, marginalize or denigrate as I do not intend it as such.

 

I want to cover 4 topics:

1) History of Blurries

2) SP1 isnt the sole cause of all blurries

3) More Details on Type 1 Blurries and Photo-scenery

4) Some systems do, some systems dont

 

1) History of Blurries, or Blurries existed prior to FSX

Here are several blog posts ( P1, P2 ) by Steve Lacey from well before FSX.

 

Here is Adam's post on AVSim.com about blurries, again before FSX shipped.

 

Here is comment by JohnMu indicating that the Google Earth flight sim can get blurries.

 

So it is clear this has been an ongoing problem and is not specific to FSX.

 

Part of the issue is the FS engine takes the approach to "run with what it’s got" instead of waiting until all resources are available. You see this with aircraft, with panels, and yes with terrain where world items render with gray/missing textures or blurry textures if the resource isn’t available within a certain time quantum. If the engine didn't take that approach, the simulation would pause which is unrealistic.

 

From the reports of blurries with GoogleSim, it appears they have made a similar design choice to favor flying and simulating the flight over rendering. That tends to validate our design choice.

2) SP1 isnt the sole cause of all blurries across the board

We need to distinguish amongst the types of blurries first.

 

I identified 4 types of blurries in this article.

 

Let’s recap them, 1 by 1:

 

Type 1) Blurries with photo-scenery.

 

As mentioned, photo-scenery is one add-on type that can be directly impacted by the multi-core changes. However, this is not "across the board" as not all users of all photo-scenery show this issue. More on this in a moment.

 

Type 2) Blurries that catch up.

 

These are usually the result from settings that are too high for a given config. Whether that is from the hardware itself or from some other local problem is hard to say. I do see quite a few people who,when they flatten their machines and start over, do not have blurries. Or who when update their hardware can run at the settings they desire without blurries. This all seems to indicate a local issue.

 

Type 3) Some tiles just a little bit blurry.

 

I believe this is from misunderstanding texture filtering and how it affects pixels, and besides developing a nomenclature for blurries explaining the relationship between texture filtering, scene filtering and AA, view angles, and zoom was the main purpose of the PDF I posted about the blurries months ago. There have been several threads on avsim.com where knowledgeble developers ( thanks Luis! ) have pointed out similar details recently.

 

Type 4) Blurries all the time

 

This seems, again, to be some local problem where the hardware/software config is just badly set up. Otherwise, how does anyone fly without blurries? That existence proof is key.

3) More Details on Type 1 Blurries and Photo-scenery

SP1 did make changes to texture composition to achieve better multi-core usage. Photo-scenery can show a negative effect from this in a special case. More on that in a bit.

 

We did 2 things in Accel/SP2 to try to mitigate the effect:

1)strengthened the IO handling

2)created an article for the SDK that helps point out to photo-scenery authors what can trigger this, including

"If aerial photography is being used to replace a large area with detailed imagery, involving the division of the target area into a large number of bgl files, there can be a significant increase in scenery load times. This can be due to an excessive amount of transparency within cells at one or more LOD level. Use the tmfViewer tool to examine the bgl files produced by the Resample tool, and note that transparent areas are shown in medium gray (see the image below).

 

If there is transparency within a cell at any LOD level, the terrain system has to load in multiple files to piece together the terrain texture for each cell. With a large amount of transparency, and a large number of bgl files containing images, this piecing together can become very time consuming. Minimize transparency within each LOD cell by preparing .inf files that target specific LOD levels. The default Destination parameter LOD=Auto should be changed to provide a minimum and maximum level, or simply one level, that minimizes transparency for the particular LOD settings. This will involve having several .inf files for each section of source data.

 

The number of bgl files used to hold image data at one level of detail should be reduced by a factor of four for the next level of detail. So, for example, if 16 files are used to hold an area at LOD 14, then four should contain all the imagery at LOD 13, and one at LOD 12. From then on there is no need to have one file for each level of detail, all the lower levels of detail can be placed in one file.

"

So that’s the advice in the updated SDK.

 

What this means is that the work in SP1 can cause an issue with certain authoring styles of photo-scenery as a consequence of parallelizing the file IO in SP1 to make better use of cores.  Once the file IOs are handled in parallel and not serialized, it is easier for FSX to pound the file system into submission and get behind if there are an excessive number of file loads. RTM with its sequential loads did not have this issue with this style of photo-scenery but did suffer from slow performance and stutters and thus had a hard limit on how far performance could go. This does not mean the design is inherently bad, just that there is a special case where it isn’t a win. The special case is photo-scenery with a lot of file IO loads and a lot of transparency. The transparency can make the situation even worse because that increases the number of loads since a single cell no longer depends on itself but on its neighbors and this makes the situation go from bad to worse.

 

This thread on AVSim.com shows that SP2 did help. This thread on flightsim.com shows that some products do work, while some older products do not. These two threads show both that there is an existence proof it is not an across-the-board problem and that there is a special case where there is a problem.

 

With that covered, lets discuss 2 photo-scenery products: Horizon's Gen-X and TileProxy ( TP ) to get specific.

 

Horizon forums don’t seem to show the same level of pain we see in AVSim forums. This thread on the Horizon forums, for instance seems to indicate all is not so tragic as some would have us believe after SP1.

 

This thread seems to indicate that the approach TileProxy uses is so vastly different from what Gen-X uses that TP and its authoring style contributes to the blurry problem, I quote:

"Using TileProxy, you would end up with 144,979 files in the TileProxy UK folders on your local drive compared with 1855 files in Gen-X folder.

"

The fact that Gen-X seems to not suffer these to the same degree that TP does would indicate that the authoring time change suggested by the Accel/SP2 SDK is an important piece of information. I have had discussions with Horizon that confirms this.

 

Let’s face it, 144,979 files is a lot. An extreme amount by any metric. Using a 4x4 technique to group the textures together would reduce that by a factor of 16 to in the 9-10k range. That would probably work. So using a 1:1 style authoring technique where there is one result texture for each source texture just isn’t going to work anymore. Yes, that is a consequence of the changes in SP1, but those changes are not inherently bad. I would say that having 144,979 files is bad and FSX hid that before SP1.

 

Unfortunately for TP, given how the data it references is stored and given the EULA issues it faces - I suspect that a re-authoring pass is hard to accomplish.

 

Net-net the tradeoff we made for performance gains in SP1 means that a new authoring style is necessary. And this is backed by real-world data in that the new authoring style actually works and end-users see a performance gain from both SP1 and SP2.

 

I suspect that, for the users that get better photo-scenery behavior when going back to RTM what is happening is they sacrifice those performance gains and that masks the loading costs that TP style photo-scenery causes in that slower FPS and more stutters exist due to all the IO happening more sequentially on a single thread.

4) Some systems do, some systems dont

Almost identical systems with and without the blurries points to a system factor. Think about it. The fact that systems A,B,C dont have blurries;and systems A', B', and C' that are almost identical do have blurries points to something unique about those systems being a contributor.

 

Else wise no system would run without blurries. This "existence proof" on the same hardware is key.

 

And many users who had blurries do not experience them when they upgrade to new hardware. This is a further existence proof that the blurries were caused by something specific and unique to that hardware configuration.

 

Unfortunately we have yet to figure out what this "unique factor" is. If we could determine what that factor was, of course we would be interested to hear about that and would examine the details.

I hope this explanation helps clarify where we are with respect to the blurries in FSX.

Comments

• Anonymous
  January 04, 2008
  Phil, thank you for this detailed blog entry and Happy New Year! Perhaps wrong FSX.cfg tweaks are causing also blurries (i think it's better to not use any tweak instead of using a false tweak). And for the FS9 Photoscenery users: Try "FS Earth Tiles" instead of the great Tileproxy tool. It took over a month until i was able to create a small Photoscenery for FSX, but with "FS Earth tiles" ( [url=http://www.fspassengers.com/forum/read.php?f=9&i=4634&t=4634]click[/url] ), it takes 5 minutes to get the images and with the SbuilderX and autogen tutorials (Avsim library), it's really easy for everybody to create FSX Photoscenery with blend and water masks and autogen. Tilproxy is really fantastic but i think it's better to use photoscenery only for selected locations (e.g. mountains and cities) and not for the whole world.

• Anonymous
  January 05, 2008
  i don't have any blurries because i now have a 45nm penryn QX9650 processor coupled with 2 GTX's, sometimes i wonder whether it's really worth all the trouble :( anyway you should make this open-source next time so any issues can be resolved more quickly with confirmation.

• Anonymous
  January 05, 2008
  Aber: there are no plans to make anything Aces does open-source. it isnt even worth talking about.

• Anonymous
  January 05, 2008
  Phil ... I don`t care about Fsx now, just tell us that Aces are going to build a new graphics engine from scratch in next version ... yes or not ??? brds and Happy New Year!!

• Anonymous
  January 06, 2008
  The comment has been removed

• Anonymous
  January 07, 2008
  Hiya Phil! Just a couple of things:

1. It's Steve Lacey, with an 'e' :-)
2. You know I love FS, but I take exception to your second point. Where in my post about Google Earth did I say that it suffered from blurries? Someone in the comments makes the assertion, but I certainly didn't. Cheers, Steve

• Anonymous
  January 08, 2008
  Quote, "I have had discussions with Horizon that confirms this." I think I speak for many people who, although frustrated the blurry issues have arisen in the first place, really appreciate your efforts in continuing to mitigate the problem. The fact you have actually spoken to a photoscenery vendor gives me great hope this problem can be solved through cooperation and communication. Happy new year! Paul Egan

• Anonymous
  January 08, 2008
  The comment has been removed

• Anonymous
  January 08, 2008
  Steve: sorry about the name misspelled, and I clarified who authored the comment.

• Anonymous
  January 08, 2008
  NicN: Its just impossible for us to investigate every system configuration. I do not believe there is a way to accomodate that in the design except for "shooting lower" in terms of features and capabilities. That isnt our first choice :-).

• Anonymous
  January 08, 2008
  The comment has been removed

• Anonymous
  January 08, 2008
  as you see ... Phil didn`t answer to my question about new engine for fs11 so... expect "better version of

• Anonymous
  January 08, 2008
  as you see Phil didnt answer to my question .. so be sure that FS11 will be still on the same graphics engine like past versions.... oh my... or Iam wrong Phil ?? ... brds

• Anonymous
  January 08, 2008
  janda: this isnt something we can talk about as plans for FS11 are not fully determined.

• Anonymous
  January 09, 2008
  Limited testing... WIth nVidia 8800, I found there were no 'blurries' to be had on my machine.(Dx9/ 10) I switched over to ATI 3870 XFire I found no 'blurries' until I ran the Fighter jet (DX10) and then only some tiles would be blurry but with the float plane (flying much slower) I had no blurries. This was at low altitude Same machine, different graphics solution, same enviromental conditions

• Anonymous
  January 15, 2008
  Problems.... that´s all there is with FSX!! Uninstalling and installing this product for maybe a hundred times... FSX, SP1, ACCELERATON,,, I´m sick of It now,, I love Flight simulator,, can It really run normally,, all the latest upgrades from Direct X, Win Update,, Recommended updates or not,, everything!! I even bought a Intel Extreme processor for this,, beacause something said this Play to win with,, !!! //sorry for my non perfect english,, I´m not american or english

• Anonymous
  January 15, 2008
  Well to be more exact,, I formated my HD for a clean FSX,, Installed the latest DX and the latest drivers for my Video, Installed FSX-RTM then added: SP1 and Acceleration,, made some adjustments to the video driver and then reboot,, then everytime I start FSX and select flight or whatever,, I try to exit the simulator or go to the menys in it,, the only thing that happens is that I´ll get a big f---in black screen,, I have to press the computers On/Off - button,, nothing else works,, this is the first time with this problem,, otherwise it´s something else,, slow fps over tree areas,, the blurries is ok,, sick of this,, my computer specs isn´t bad at all,, well over minimum and some more with my quite new QX6850 Extreme processor 4GB of RAM Win Vista X64 and 7950gx2!!!!!!

• Anonymous
  January 15, 2008
  Dojjan: this is not tech support.

• Anonymous
  February 04, 2008
  The comment has been removed