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General => Terragen Discussion => Topic started by: Clay on October 13, 2015, 12:49:28 AM

Title: Another reference pict
Post by: Clay on October 13, 2015, 12:49:28 AM
A friend from back home took this shot from her backyard, no photoshop or anything, that's what nature's beauty looks like in it raw form!
Title: Re: Another reference pict
Post by: Upon Infinity on October 13, 2015, 01:14:47 AM
Yeah, most of this could be done with Terragen.  I'm working on some similar stuff.
Title: Re: Another reference pict
Post by: AP on October 13, 2015, 01:30:02 AM
The ground debris would be the most challenging part. 3d leaf piles, branches, twigs and so on.
Title: Re: Another reference pict
Post by: Tangled-Universe on October 13, 2015, 04:16:13 AM
What I noticed quite immediately was how the water is reflective and not transparent.

So is this just a matter of different conditions adding up to this result?
Or is it because he/she used a polarisation filter attached to the lens to enhance the differently (from transparency) polarised light?

Debris and all those elements would indeed be a big challenge, but like with any good CG scene it's mostly a matter of countless iterations and time.
Title: Re: Another reference pict
Post by: bobbystahr on October 13, 2015, 12:30:34 PM
Has a polarised look to me...Great photo reference Clay...saved.
Title: Re: Another reference pict
Post by: masonspappy on October 13, 2015, 07:04:53 PM
Lovely image! :)
Title: Re: Another reference pict
Post by: mhall on October 14, 2015, 05:25:06 AM
That doesn't particularly jump out as a polarized image to me.

Obviously, it depends on how it's used, but one of the reasons for using a polarization filter is to *remove* reflections, haze, etc. from the image.

This just looks to me like a regular shot with the camera's saturation pumping the colors somewhat.

IMO.

~m
Title: Re: Another reference pict
Post by: Tangled-Universe on October 14, 2015, 05:52:21 AM
Quote from: mhall on October 14, 2015, 05:25:06 AM

Obviously, it depends on how it's used, but one of the reasons for using a polarization filter is to *remove* reflections, haze, etc. from the image.

~m

No, that's a misconception.

It's the most used situation, to remove reflections, but it's not what a polarizer is about.

You can rotate a polarizer to have it to remove reflections, but if you simply rotate further you can actually *enhance* reflections.
Title: Re: Another reference pict
Post by: Dune on October 14, 2015, 07:45:59 AM
Did some quick lookup:



The answer will be easy to figure out if you understand a little bit what polarization means.

I don't have a polarizing filter to play with, but I do have a physics degree, so here it goes:

Light reflected by certain types of surfaces (such as glass or water, but not metal) is partially linearly polarized. Light reflected under a certain angle is fully polarized.

Linear polarization means that the electromagnetic wave (light) vibrates in a certain plane only, to put it simply. If you rotate the polarization filter to align with this plane, it lets the polarized light through. If you rotate it to orient it 90 degrees to the plane of polarization, it filters it out fully.

Sunlight will contain light of all polarizations, so a polarization filter will only filter "half of it". Reflected light contains more of light polarized in a plane parallel to the reflecting surface: so if you align the polarization filter perpendicular to the reflecting surface, it will filter out more of the reflected light than light coming from elsewhere. If you orient it parallel to the surface, it will filter out less of the reflected light---the effect you are looking for.

So the short answer is: just rotate the polarization filter and find the orientation which makes the reflection look the brightest! This will accentuate the reflections in the photo instead of suppressing them.

EDIT: Here's an extra idea: you could take two photos, one where you minimize the intensity of the reflections and one where you maximize it. Using these two images, you could make the reflection even stronger by subtracting some of the relfection-less image. It'd take some experimentation with an image processing package to see if it is possible to get it right.
Title: Re: Another reference pict
Post by: Daniil on October 14, 2015, 07:54:26 AM
Quote from: Dune on October 14, 2015, 07:45:59 AM
EDIT: Here's an extra idea: you could take two photos, one where you minimize the intensity of the reflections and one where you maximize it. Using these two images, you could make the reflection even stronger by subtracting some of the relfection-less image. It'd take some experimentation with an image processing package to see if it is possible to get it right.
There is just one problem: If you are taking a photo of a real water (with motion, ripples etc) reflecting natural environment (with wind), you should take both photos at the same time from the same place.  ;D
Title: Re: Another reference pict
Post by: mhall on October 14, 2015, 05:33:41 PM
QuoteNo, that's a misconception.

Ummm ... no, I don't think that's a misconception. Unless landscape and product photographers have been using polarizing filters incorrectly for decades and just didn't know it? :)

Now, I will say I've never considered using a polarizing filter to enhance reflections, so if you mean that, then I may agree. I could see how, by removing polarized light unrelated to a reflection you could enhance the look of it, but, like I said, I've never used them that way.

Title: Re: Another reference pict
Post by: AP on October 14, 2015, 05:58:32 PM
Does not a polarize filter do nothing more then simply diffuses light therefore softening strong specular and reflective sources?
Title: Re: Another reference pict
Post by: mhall on October 14, 2015, 11:55:51 PM
I was thinking of TU's comments on the way home from a shoot today. And I suppose, depending on how you look at it, a polarizer DOES only enhance reflections ... if you consider the fact that *everything* we see is a reflection and you use a polarizing filter to block *unwanted* reflections and only show those that you want. The fact that the ones which are typically unwanted are usually referred to as reflections and the reflection we often want to see is the diffuse color of a subject is a matter of semantics. :)

Chris, here is a good article with examples:

http://www.cambridgeincolour.com/tutorials/polarizing-filters.htm

Regards,
Micheal

Title: Re: Another reference pict
Post by: AP on October 15, 2015, 01:34:21 AM
A very informative article. I used to have a pair of sun glasses that were well polarized, grey filtered and it helped a lot with the sun glare.   
Title: Re: Another reference pict
Post by: Tangled-Universe on October 15, 2015, 04:16:50 AM
Yes, all the light in the sky is polarized in all possible *orientations*. This is what polarity is about.
Light is electromagnetic where the electric and magnetic are perpendicular to each other.
In 3D the orientation of that construct could be anything, be it upright or upside down. Doesn't matter.

There's no thing as "fully polarized" or "partly polarized" if you don't know the polarization of the incidence ray.
The strength of the effect is based on the combination of angle of view and angle of lightsource to the viewed point/object.
Point a polarizer filter to the sky while facing the orientation but not directly at the sun and the effect of your polarizer is very minimal.
Point a polarizer filter to the sky while facing away from the sun, right behind you, and the effect of your polarizer is quite massive.

Reflected light indeed has a different polarity from it's incident light, as Ulco pointed out.
With a polarizer you block certain "orientations" of the light wave and it depends on how you rotate the filter.
For reflections you can turn the filter to let all that reflected light get through on your film/sensor and since the orientation of the filter in the meantime partly blocks the light of other polarizations, you are basically "enriching" the light for reflected light. Thus stronger reflections.
Obviously you can also do it the opposite way and reduce (but never completely remove) reflections greatly.
Title: Re: Another reference pict
Post by: Tangled-Universe on October 15, 2015, 04:21:38 AM
Polarization filters are quite awesome, because they can do things you will NEVER be able to do in post, because you're physically filtering light.

It's not only useful for reflections of water and such, but especially useful for enhancing contrast in sky and clouds and also to make colors "pop" in a unique way which is also impossible to do in post.

See a great example here which I shot in New Zealand 2 years ago:

http://www.planetside.co.uk/forums/index.php/topic,17749.msg172028.html#msg172028
Title: Re: Another reference pict
Post by: mhall on October 15, 2015, 05:47:46 AM
Most definitely agreed they are not just for water just typical reflections - I should have made sure I wasn't trying to argue that from start when I spoke of reflections.

Haze is in fact reflections from particles in the air (which comes back to that "everything is a reflection" point in my last post). The polarizer is helping to remove those and give you that pop. It's the same for greener or more colorful/saturated foliage. As the polarizer is adjusted to filter the light you don't want, you see the truer color of the plants more intensely.

Polarizers also make a great neutral density filter in a pinch and I have used them that way on occasion when I didn't have a proper one available. :)

I like that shot in your other post - I remember seeing that!

~Micheal
Title: Re: Another reference pict
Post by: Tangled-Universe on October 15, 2015, 05:50:36 AM
Yeah a polarizer takes away about a stop or a bit more. Depends on the brand/make.
Ideal for allowing some motion of water during daylight shooting, because nothing looks worse than shots of water faster than 1/30th of a second.
Title: Re: Another reference pict
Post by: bobbystahr on October 15, 2015, 12:49:44 PM
Well...I certainly learned a bunch of stuff here...Thanks T-U
Title: Re: Another reference pict
Post by: El Kabong on October 15, 2015, 03:12:39 PM
Yeah Bobby, same here, but all that science took the majik right out of it....    ;D
Title: Re: Another reference pict
Post by: AP on October 15, 2015, 06:23:50 PM
Quite enlightening particularly if you are a photographer.
Title: Re: Another reference pict
Post by: WAS on October 15, 2015, 08:30:31 PM
Quote from: Chris on October 13, 2015, 01:30:02 AM
The ground debris would be the most challenging part. 3d leaf piles, branches, twigs and so on.

What I was thinking too. Does anyone have a good source for ground logs/branches etc?
Title: Re: Another reference pict
Post by: bobbystahr on October 16, 2015, 02:14:26 AM
Quote from: El Kabong on October 15, 2015, 03:12:39 PM
Yeah Bobby, same here, but all that science took the majik right out of it....    ;D

Dunno, I always thought science and magick were different expressions of the same energy