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brucek

HDR- on or off?

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Who uses HDR on in XPX?  I have been using it for some time, and last night while playing with a profile in NI (I got the information for the profile from another thread here),  I tried turning HDR off.  I was actually quite amazed with the lighting effects of having HDR turned off,  the lights were larger and seemed more realistic.  I really don’t understand what HDR does, so what am I missing (in eye candy and/or performance) with it turned off?

 

Thanks,  Bruce.

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To understand that, some technical detail are needed to be known. I'll try to explain, without using any weird term!

 

The light you see is nothing more than a... texture! This textured is rendered that way that appears only (and how) from specific distances and angles from the view point. Most of the lights you see are not "real" lights, they are not affect their surrounding objects. Authors "mimic" the lighting on an object, by "baking" in a 3D software how a light affects an object and have a second texture for that object when the lights are on (like in the night).

 

What HDR-ON does is that give to the lights...life! X-Plane's rendering engine computes how each light will affects it's surrounding objects and render those objects accordingly. 

 

Here is an example: There is an airplane (cold&dark) in the apron!

 

First picture HDR-OFF. Can you see it?

 

Second picture HDR-ON. The light from the pylons is lighting up everything!

 

 

 

 

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HDR on. As Airfighter explained, HDR lights are "real" lights, i.e. calculated in real time and dynamically affecting the environment, whereas non-HDR "light" are no lights at all. Most noticeable effect is when you are on an airport at night. Without HDR, you'll usually see nothing (except maybe terminal buildings).

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Of course, there are some trade offs. A deferred renderer can show an awful lot of lights and other nifty effects, but antialiasing is harder to accomplish and often less effective except in modes that require a very very powerful GPU.

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Definitely on. Although that means I have to set some things lower or put up with occasions frames drops, the world looks so much more realistic with it on.

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I leave it off.  It certainly looks great, but it tanks my framerates.  I like lots of objects and trees, but I can't have that and HDR.

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I actually like the looks and think it looks more realistic from the air  with it off...

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Thanks for the interesting replies.

 

So, HDR adds secondary effects to the light textures that mimic the effect on adjacent textures of real lights, do I have that correct? In my XPX setup (which could very well be mis-adjusted...), the HDR lights look like small "pin-pricks", but non-HDR lights are larger and exhibit some light-bloom, from my own limited RL night flying more realistic. Maybe I have my HDR lights mis-adjusted or otherwise screwed up.....

 

One thing I have noted in support oh HDR light textures is that the white/red lights of road traffic at night time seems to stand out more with HDR turned on, and lights on runways that are tangential to the runway I am approaching (at KORD, for example) seem more pronounced with HDR turned on. So, I assume that HDR light textures are more multi-directional in their "luminance"... at least thats what it looks like to me.

 

Thanks again for the answers. I don't have a frame-rate issue with HDR turned on, so that's not an issue. It's just that the non-HDR light textures look better to me, if I ignore the aspects of their effect on adjacent textures, etc.

 

Thanks, Bruce.

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From Ben Supnik.

 

 

Why is HDR Mode So Weird

This begs the question: why is HDR rendering so weird?  Why does it look different from non-HDR rendering, and why doesn’t it look the same as v9?  What did you guys do?

There are a number of changes to how we render in X-Plane 10, some specific to HDR rendering, and some sim-wide.

  • The entire sim now works with a linear lighting equation.  Basically when the sim performs lighting  calculations on the GPU, it thinks in terms of photons and not colors, which produces more realistic results in most cases.  With lots of light sources, linear lighting is absolutely necessary for combining those lights.
  • The order of rendering operations is very different between HDR and non-HDR mode, and the formats that they render into (24-bit RGB vs. floating point, etc.) are very different.  HDR is fundamentally a two-pass format.

X-Plane maintains two separate rendering paths for HDR vs. non-HDR and they are quite different in both what happens at each stage and when the stages occur.

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I don't have a frame-rate issue with HDR turned on, so that's not an issue.

 

Thanks, Bruce.

You lucky git!

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You also get heat exhaust effect off of jet engines with HDR on, so if you like to fly mostly external views it's definitely nice to have on. Also I think you get nicer atmospheric scattering effect in the daytime too.

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Thanks again everyone.  I have no picked up Chris K's file and are currently using option 2…  looks awesome,  with HDR on.  After the helpful info in this post, HDR now means a lot more to what I am seeing.

 

Thanks, Bruce.

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You lucky git!

-----------------------------------

Same here, actually. I have HDR as on, things set to 'tons', trees set to filled in, the world as medium, shadows as 3D on cockpit, HDR set to all '4's, and have N.I. set to respect XPX internal settings. I usually hover between 26-30 FPS, which I have locked at 30 inside XPX. Man..I had better never get rid of the Dell 'beastie'.....and run with UrbanMaxx 3D v2.0

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Mine's off, for bigger frames... Maybe if I ever get a better video card I'll use it on...

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Mine's off, for bigger frames... Maybe if I ever get a better video card I'll use it on...

---------------------------------------

J...night looks so good, soooooo gooood at my .org KFNT with it set to on. It sort of takes your breath away...and the way the surfaces look...the word: realistic/real world! I keep giving my head a shake, with each night-time taxi out to the active. Water landings, moon reflections, cloud reflections...XPX and HDR rocks!

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Is it simply a vram thing? I only have 1.5GB so I guess that's why I see such a big frames difference in on and off.

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Is it simply a vram thing? I only have 1.5GB so I guess that's why I see such a big frames difference in on and off.

I noticed that no matter what you do in xplane, if you get too close to the edge of your VRAM you WILL stutter.

 

Period.

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Interesting. My gtx570 only has 1.28GB. I wonder if that's what causes the stutters... Cause I get stutters and fps drop like crazy in big cities with HDR on.

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Interesting. My gtx570 only has 1.28GB. I wonder if that's what causes the stutters... Cause I get stutters and fps drop like crazy in big cities with HDR on.

You can push a whole lot of polygons in this sim as long as you keep an eye on the ram usage. At least that's how it seems to me so far. I've been experimenting a lot to find the best balance. (on my system)

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Who uses HDR on in XPX?

 

 

On, at night.

Looks simply to good, even on my rather low end PC.

 

 

 

 

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Yeah it's great below 3000 AGL, but the higher you get the roadway lighting disappears (at the edge of the scenery tile). This is a major annoyance IMHO.

 

Unless someone can tell me how to fix this.... Kills the realism

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