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General => Terragen Discussion => Topic started by: sonshine777 on April 24, 2008, 09:57:10 AM

Title: Camera POV and Scale
Post by: sonshine777 on April 24, 2008, 09:57:10 AM
One of the things I have been striving to achieve in creating scenes with TG2, is to set my POV to the same location as my camera would be when I am taking a photograph (1 to 2 meters). This is the point of view I do most of my renders from, which is where my problem begins, at that elevation I can't get the rocks and dirt to look real. I can always raise the camera so it is several meters (10 to 20) above the ground and get the rocks to look ok, but this doesn't work when I am using a real-world DEM for a terrain. Most of the terrains that I use are actual DEM's of real locations, I seldom use the generate terrain feature of TG2. I want my mountains to appear the correct size in comparison to the trees, plants AND ROCKS in the foreground. If I have to raise the camera to make the rocks look good I then have to increase the scale of the trees and plants which in many cases throws the scale of the background mountains and hills.

I see so many amazing images of great rocks that appear to be close up point of views, but I seldom see plants or trees with them. So, my question is, what is the average height of your camera above the ground when you render?

Just thought it was a good question to ask.

If some of these renders have the camera at 1 to 2 meters above the surface I would love to get a .tgd or .tgc to look at and see where I am going wrong.

Thanks

Tom
Title: Re: Camera POV and Scale
Post by: Tangled-Universe on April 24, 2008, 11:29:51 AM
Looking at your problem the first thing I'd do is to place a tree-population in the scene and make it fit the scale for the background you have in mind.
Write down the scale-settings and remove/disable the population. Import a single model and place it at/nearby your POV at 1-2m camera-heigth (rendering single model goes lots faster)
Set up a crop render showing the lower part of the tree and your ground/soil.
Now add powerfractals and fake stones until you get something with good scales in comparison to the tree.
Once finished remove the single tree and enable the population or reload it and set the proper scale-values.
You should now have a nicely scaled foreground with properly scaled trees to the DEM-terrain.

I don't really run into these problems because I don't use DEM's that much...an advantage then is that scale is just perception. I can add a camera at 20m heigth in a way you would never notice it. It's all just relative, but with DEM's I can imagine it can be a bit harder.
Enough said, I think this is the approach I'd try. Hope this helps.

Martin

edit: oh yeah...maybe adding a sphere as reference might also help...
Title: Re: Camera POV and Scale
Post by: sonshine777 on April 24, 2008, 11:44:03 AM
Thanks Martin, most of the things you suggested I have tried or currently use in the creation of scenes.

I guess my goal is to find a way to get the camera at 1 to 2 meters off of the ground so I don't have to use a forced perspective approach.

Tom
Title: Re: Camera POV and Scale
Post by: Tangled-Universe on April 24, 2008, 12:22:12 PM
I see what you mean...
Well, maybe the last lines I told are probably the most important:
scale is relative, so don't stick to the 1 - 2m, as long as the impression of camera at 2m heighth is there then it's good. Don't fix/focus too much on real-world numbers.

Martin
Title: Re: Camera POV and Scale
Post by: sonshine777 on April 24, 2008, 12:26:45 PM
I know I may have to settle for impression, but one cae always hope. ;D
Title: Re: Camera POV and Scale
Post by: RArcher on April 24, 2008, 12:31:49 PM
Tom,

I try to do most of my renders with the camera between 0.5m and 2m off the ground as well.  For the most part I find that I just need to keep trying smaller and smaller values with regards to the power fractal scaling's until I find something that works.  I'll include a .tgd of one of my files that has rocks and vegetation.  It isn't the best and the rocks can certainly use a lot more work but it "might" help in regards to scaling.  I can't guarantee that any of what I did with this file will make any sense though, as you might expect from the result I received.  ;D

-Ryan Archer
Title: Re: Camera POV and Scale
Post by: sonshine777 on April 24, 2008, 12:35:22 PM
Thanks Ryan, I will take a look.
Title: Re: Camera POV and Scale
Post by: Seth on April 24, 2008, 12:47:32 PM
i don't care about how high my camera is... i just play with scale.. everything is relative...
first, i put my rocks (fake stones and all, and then i set the vegetation sclae...
but i understand that you want to have evrything put in the right (real) scale... can i ask you why ? i mean... i don't see the point to complicate things so...
my suggestion will be to use a sphere... as T-U suggested... it's the only way i see...
Title: Re: Camera POV and Scale
Post by: RArcher on April 24, 2008, 12:57:48 PM
Scale may not matter much for a single one off image, but if ever you plan to do any animating, or a scene from multiple points of view it certainly becomes more important.  Most values in TG2 seem to be in meters so it makes sense to me to try and keep things in actual size in order to make it easier to relate to what I see and can measure around me.
Title: Re: Camera POV and Scale
Post by: sonshine777 on April 24, 2008, 12:58:02 PM
Quote from: seth93 on April 24, 2008, 12:47:32 PM
i don't care about how high my camera is... i just play with scale.. everything is relative...
first, i put my rocks (fake stones and all, and then i set the vegetation sclae...
but i understand that you want to have evrything put in the right (real) scale... can i ask you why ? i mean... i don't see the point to complicate things so...
my suggestion will be to use a sphere... as T-U suggested... it's the only way i see...

If you just generate a terrain and build your scene from that then scale isn't relative. But I like using DEM's of real places. One example is Timothy Lake in Oregon, the lake is about 1.5 miles across and Mt Hood is 6 miles beyond that. In order to get the rocks on the shore to look good I have to raise the camera about 20 meters off the ground and scale the plants and trees to look correct. The problem is, now the lake looks like it is only 300 yards across and Mt hood appears to be only 1 or 2 miles away. This is why it is important to get the scale right. Of course that is just my opinion.
Title: Re: Camera POV and Scale
Post by: SeerBlue on April 24, 2008, 01:10:41 PM
Atmosphere and lighting can have quite an effect on perceived distance in a render, I don't know if this is the case in your render, I just thought back to my tg.9 days when I first learned how much difference the haze settings made.
Title: Re: Camera POV and Scale
Post by: Seth on April 24, 2008, 04:03:42 PM
Quote from: sonshine777 on April 24, 2008, 12:58:02 PM
Quote from: seth93 on April 24, 2008, 12:47:32 PM
i don't care about how high my camera is... i just play with scale.. everything is relative...
first, i put my rocks (fake stones and all, and then i set the vegetation sclae...
but i understand that you want to have evrything put in the right (real) scale... can i ask you why ? i mean... i don't see the point to complicate things so...
my suggestion will be to use a sphere... as T-U suggested... it's the only way i see...

If you just generate a terrain and build your scene from that then scale isn't relative. But I like using DEM's of real places. One example is Timothy Lake in Oregon, the lake is about 1.5 miles across and Mt Hood is 6 miles beyond that. In order to get the rocks on the shore to look good I have to raise the camera about 20 meters off the ground and scale the plants and trees to look correct. The problem is, now the lake looks like it is only 300 yards across and Mt hood appears to be only 1 or 2 miles away. This is why it is important to get the scale right. Of course that is just my opinion.

I truly understand your problem. And you're totally right...
I never tried to work on DEM... so I am not able to help you on this.
but if you put your cam only 2 meters high, put good fake stones and real scale vegetation, what happen ?
Title: Re: Camera POV and Scale
Post by: sonshine777 on April 24, 2008, 04:24:34 PM
Quote from: seth93 on April 24, 2008, 04:03:42 PM
I truly understand your problem. And you're totally right...
I never tried to work on DEM... so I am not able to help you on this.
but if you put your cam only 2 meters high, put good fake stones and real scale vegetation, what happen ?

Here is a recent example.

http://forums.planetside.co.uk/index.php?topic=3886.0

The rocks in the foreground.
Title: Re: Camera POV and Scale
Post by: Seth on April 24, 2008, 04:27:04 PM
i saw this one, it looks like you're only 30cm high...
Title: Re: Camera POV and Scale
Post by: Tangled-Universe on April 24, 2008, 04:32:05 PM
Yes exactly...
To stay on the scale-topic...in that particular case I'd make the flowers a tad smaller (in relation to the trees, you see).
And if the camera is at 2m heighth there then just increase it to 10m or so and then you'll have it :)
I don't really see big scale problems in that image.

And just like Seth and I told before, don't worry about it...
Real-world scales are only important in animations, like RArcher said.
Title: Re: Camera POV and Scale
Post by: sonshine777 on April 24, 2008, 04:32:55 PM
About 1 meter actually.
Title: Re: Camera POV and Scale
Post by: gregsandor on April 24, 2008, 04:56:09 PM
I work almost exclusively with real-world dem data, and for renders where the camera is to be hand-held, I locate the camera around 1.6 or 2 meters above the ground.  Be careful to check proper scale when using objects made by others; sloppy work in scaling will cause no end of trouble.  If your terrain is real and your camera matches the real one, you can modify the objects and goroundcover to fit, not the other way around.  I made a 1 meter cube and a 10 meter cube to check scale.  Guesswork is fine for some but you are on the right track to really getting a controlled image. 



Quote from: sonshine777 on April 24, 2008, 09:57:10 AM
One of the things I have been striving to achieve in creating scenes with TG2, is to set my POV to the same location as my camera would be when I am taking a photograph (1 to 2 meters). This is the point of view I do most of my renders from, which is where my problem begins, at that elevation I can't get the rocks and dirt to look real. I can always raise the camera so it is several meters (10 to 20) above the ground and get the rocks to look ok, but this doesn't work when I am using a real-world DEM for a terrain. Most of the terrains that I use are actual DEM's of real locations, I seldom use the generate terrain feature of TG2. I want my mountains to appear the correct size in comparison to the trees, plants AND ROCKS in the foreground. If I have to raise the camera to make the rocks look good I then have to increase the scale of the trees and plants which in many cases throws the scale of the background mountains and hills.

I see so many amazing images of great rocks that appear to be close up point of views, but I seldom see plants or trees with them. So, my question is, what is the average height of your camera above the ground when you render?

Just thought it was a good question to ask.

If some of these renders have the camera at 1 to 2 meters above the surface I would love to get a .tgd or .tgc to look at and see where I am going wrong.

Thanks

Tom

Title: Re: Camera POV and Scale
Post by: Mr_Lamppost on April 24, 2008, 07:55:51 PM
Even though I work with procedural terrains I always work at 1 to 1 real world scale.  I just find it easier that way, lots of my scenes use functions so scale is important.  I am not that bothered about flying cameras but if objects form an important part of the composition I place the camera 1.7 metres above the ground. I am not a great user of fake stones so can't guide you there.

One of the biggest problems I have found is the scale of imported objects. This varies wildly and can be a real spoiler of scenes, objects are often 10 or 100 times larger or smaller than  they should be; commonly but less frequently off by a scale of 3.  I have found this type of scaling error creeping in during the conversion process.  Build an object in Wings 3D using 1 arbitrary unit as equal to 1 metre, save as .obj and import to Terragen; no problem.  Open the .obj in Blender to apply uv mapping and resave; import to TG and the object is only one tenth the size it should be.  The rescale occurs at the import to Blender stage but as Blender's unit is also arbitrary this is not immediately obvious.  The scale by 0.3 or 3 is probably the result of  an unnoticed conversion from feet to metres.

Rimmer moment (Double salute and emphasis on the RIM*).  If I say it's a 6m lighting column you can be sure it is 6m above ground, actual lamp height may vary slightly depending on lantern used.
* Make it sound like a toilet cleaner: RIM-mer.  ;D  

To get around this problem I made myself a set of reference grids and check the scale of objects against these before I use them, applying appropriate corrections to scale as required. I posted a download link a couple of weeks ago, the title of the thread was probably not that helpful but it can be found here: 

http://forums.planetside.co.uk/index.php?topic=3766.0

The request for the inclusion of reference human figures has not been forgotten.
Title: Re: Camera POV and Scale
Post by: sonshine777 on April 24, 2008, 09:24:51 PM
Thanks Mr_Lamppost for your input, Scaling the models hasn't been the problem per say. I have used you grids and they work great. I used the 10 cm one to scale the butterflies I have posted recently. My problem has been getting the scaling small enough to make the dirt look like dirt and not dirt clods. If you go too small on the scaling you end up with all kind of interesting thing protruding out of the ground, or everything goes black. I intend to keep playing with it, I just started the thread to see if anyone else was doing renders from ground zero so to speak.
Title: Re: Camera POV and Scale
Post by: gregsandor on April 24, 2008, 10:39:26 PM
Quote from: sonshine777 on April 24, 2008, 09:24:51 PM
Thanks Mr_Lamppost for your input, Scaling the models hasn't been the problem per say. I have used you grids and they work great. I used the 10 cm one to scale the butterflies I have posted recently. My problem has been getting the scaling small enough to make the dirt look like dirt and not dirt clods. If you go too small on the scaling you end up with all kind of interesting thing protruding out of the ground, or everything goes black. I intend to keep playing with it, I just started the thread to see if anyone else was doing renders from ground zero so to speak.

To solve the "things protruding too much" problem, make sure you also scale your displacement using real-world measurements.  Displacement multiplier of .01 is a centimeter, which is a pretty tall grain of sand.  If you want small grains of dirt, make sure to tell TG to make them small.  Scale those clods down to .001 and see what happens.

And there are some of us "doing renders from ground zero," with real data.
Title: Re: Camera POV and Scale
Post by: Matt on April 25, 2008, 12:33:43 AM
Quote from: gregsandor on April 24, 2008, 10:39:26 PM
To solve the "things protruding too much" problem, make sure you also scale your displacement using real-world measurements.  Displacement multiplier of .01 is a centimeter, which is a pretty tall grain of sand.  If you want small grains of dirt, make sure to tell TG to make them small.  Scale those clods down to .001 and see what happens.

Ideally that is what you should do. Unfortunately the Power Fractal starts running into problems with values as small as 0.001, as in this thread:

http://forums.planetside.co.uk/index.php?topic=3883.0

There are probably ways to avoid aftefacts though, if you use a blend shader to fade the fractal to 0 in the distance. You could do this with the Distance Shader.

Otherwise, bring out the Fake Stones Shader and increase its density. You should be able to make very small features with that.

Matt
Title: Re: Camera POV and Scale
Post by: sonshine777 on April 25, 2008, 12:50:28 AM
Thanks Matt, I will try playing with it, I never thought of using the distance shader to blend the fractal.