screen mapping - matte properties - I'm completely confused

[flipside]

I was testing with the blochi scene http://www.blochi.com/gfx/hdri/

I got pretty good results:


Only the table top is modeled and I assigned a material to it with the backdrop image of the room used as texture in the diffuse slot, environment mapping - screen. I tried with a matte material too (vraymtlwrapper), but then in reflections and refractions you see the material that's inside the mtlwrapper.

Then I saw this:
http://hdri.cgtechniques.com/~blochi/show.php?id=337
with this anim:
http://www.le-pob.pwp.blueyonder.co....maptest001.avi

This is great! He used LW, with this tutorial:
http://www.newtek.com/products/light...a_mapping.html

I tried the same thing, but in max. Now here's my problem! I can set up everything, and render a still image, but I can't pan or rotate the cam as in the tutorial.

Here's a short part out of the tut:
"The basic set up is now finished. Let’s review what is going on before we move forward. The camera and objects were set up to roughly match the original photograph. Employing Front Projection Mapping we can now see in Open GL that our 3D geometry blends very nicely with the projected image. By using “Fixed Projection” the texture is going to always be projected from where the camera is at Frame zero. This means that if we go to a later frame in the scene and move the Camera we will see the illusion of 3D space."

I have no clue how to achieve this in max...

I have a second problem! With this scene, which is quite similar to the table/room scene, I cannot put any reflective materials in it, or they show up like this:


In fact this scene uses exactly the same approach as the table one, I applied materials in the same way, but here it doesn't work, while I have no problems with reflective materials in the table scene.
see here:


Any suggestions?

I hope someone read this post untill the end

I just started playing around with this photo+3d stuff, so maybe I'm missing some important basics here?

maybe somebody can give me a general approach on how to blend 3d objects into an existing real life pic. I'm totally confused about the matte properties in the vraymtlwrapper, screen mapping, and there's another thing where you can mask out 3d objects so they look like they're partially behind for example a building or a hill (don't remember it's name...)

Phew my explanation is as chaotic as my mind right now, I need some clear simple explanations now

Thanks for any help!

regards,

flipside

[J_Bug]

Somewhere here you can find a great example.

http://www.dvgarage.com/

I'm gona look around but you may find it brfore me

--Jon

[J_Bug]

Here it is:
http://216.127.92.205/samples/maplab/maplab_teaser.mov

But now you have to tell us about that image if you can

Those boxes look cool and it also looks asif you've made an HDRI of that scene too.

--Jon

[pengo]

Always a great works flipside

Always a great works flipside

But a little critique on the first image about the glasses that seems to float (floating)

what's the settings?

bye and thenks for the great works and the support continuos

excuse my bad english

[flipside]

Well that boxes scene is just the same as this:
http://www.newtek.com/products/light...a_mapping.html

It's a real pic, and then basic shapes are modeled and the camera is adjusted so this geometry matches the background pic. This geometry will only serve as shadow catchers from the other objects you want to add to the scene.

But this is all described in detail in the link above.

I thought maybe some people who already worked with 3d geometry placed in existing backgrounds could share some insights about the problems of my original post.
Why is the chrome sphere letting the background shine through, and is there a way to 'fix' the screen mapping so you can move the camera?

J_Bug, I don't have a hdri of that scene... I do have one from the blochi scene:
http://hdri.cgtechniques.com/~blochi/show.php?id=322
Here you can find all kinds of downloads for that scene.

Pengo, indeed the glasses float... It's a vraymtl with a falloff map in the reflection slot:
http://users.pandora.be/stor1/vray/falloff.gif

[oconv]

very nice, i like your shadows
i only get weak and inaccurate
how did you achieve them?
is it only the hdri map?
if yes, what settings?

-oconv

[flipside]

I just put the hdri map in the vray skylight slot. Irradiance map -3,0; clr=nrmth=0.3

That's it!

[FutureMan]

I think the reason the reflections don't work in the boxes scene and do in the table scene is because the boxes scene isn't hdri while the table is.

[dbuchhofer]

I'm gonna hazard a guess here, The boxes scene is a screen mapped image, while the table is a spherical envieronment map..

[flipside]

They both use screen mapping as textures (tabletop - boxes - groundplane)

They both use the reflection override slot from Vray, the table scene uses a hdri and the boxes just uses a color.

[Sushidelic]

Hi!

I was quite irritated when reading the thread, but in fact it looks like it hasn't been eyplained yet what flipside had asked for, so here some basics:
There are many different mapping types in max for many different situations.

1. Environmant mappings, supporting types like screen (in another post someone asked why he doesn't get distorted refractions when inserting a glass sphere in front of a screen mapped environment. This is because it's an orthogonal projection on the background, replacing everywhere reflection and refraction with the BG, as this map has no place in space or a distance). Other environmentr mapping types refer to a 360° view, or rather how the maps are projected on a surrounding sphere. Those are f. ex. cylindrical, spherical (also known as lattitude/longitude or polar), or like in vrayhdri mirrored ball. It's kind of a pointmapping from the cameraorigin, so it is a perspective mapping onto infinity that needs a perspective view and can therefore be used for proper reflections or refractions (try assigning a spherical mapped viewport BG to an orthogonal view...).
2. UVW mappings - should be familiar - and Max also supports the feature you were looking for, camera mapping. It is a perspective UVW mapping (that's why it is often called "perspective mapping") that uses a camera as a projector to supply texture coordinates for objects (not the environment) and is f. ex. essential for image based modeling. It's under modifiers...and I wanted to explain it now, but i just found that it's all perfectly explained in max help, so i do a copy/paste and get a "post truncated"

-------------start maxhelp

There are four types of environment coordinates:

Spherical
Cylindrical
Shrink-Wrap
Screen

The first three are the same as those used by the UVW Map modifier. If you imagine a sphere, infinite in size, surrounding your scene and mapped with spherical mapping coordinates, you can visualize the effect you get with spherical environment mapping. Shrink-wrap wraps the map around a giant sphere, leaving only one singularity. Cylindrical is like a giant cylinder.

The Screen system maps the image directly to the view, with no distortion. It's similar to planar, in that it's like a giant backdrop hung in the scene. Unlike the other environment mapping methods, Screen is locked to the view. When you move the camera, the map moves with it. Therefore, you can only use it for still renderings, or animations in which the camera doesn't move.

To use a bitmap with any environmental mapping system other than Screen, you need a high-resolution map because of the size of the virtual sphere, or cylinder.

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

Camera Map Modifier (Object Space)

The Camera Map modifier (object-space version) assigns planar mapping coordinates based on the current frame and the camera specified in the Camera Map modifier. The World Space version of the Camera Map modifier updates the object's mapping coordinates on every frame.
The following steps show how to apply the Camera Map modifier, and how to set up your scene.

To apply the Camera Map modifier:

Create a scene with a camera and one or more objects. Make sure the object you want to map is visible in the Camera viewport.

Select the object, and apply the Camera Map modifier.

Use the Object-Space Camera Map modifier, the one without the asterisk.

If you have animation in the scene, move to the frame where you want the object map to match the background. For example, if the camera is animated, the mapping will match only at this frame.

On the Camera Mapping rollout, click Pick Camera, and then select the camera used for the rendered view.

---

Camera Map Modifier (World Space)

The Camera Map world-space modifier is similar to the Camera Map modifier, in that it applies UVW mapping coordinates to the object based on a specified camera. As a result, if you assign the same map as a Screen environment to the background as you apply to the object, the object is invisible in the rendered scene.

The main difference between the world-space version of Camera Map and the object-space version is that, when you move the camera or the object using the object-space version, the object becomes visible, because the UVW coordinates are fixed to the object's local coordinates. When you move the camera or object using the world-space version, the object remains invisible because world coordinates are used instead.

---------------------------end maxhelp

Hope this helps you a little bit and makes sense, and always remember, you don't see any background in this animation (exept reflections/refractions), it's all matched geometry where each object was perspectively mapped, each with its handretouched version of the photo and 100% self illuminated. Enough basics now.

Greetings, Michael

[flipside]

Hey thanks for your clarifying post! It put me on the right track!

Here's the first testresult:
http://users.pandora.be/stor1/vray/brix01.AVI

(divx5 codec)


Few questions though:
- why were you irritated by this thread?
- why 100% self illumination? (and how to do it with vraymtl, it doesn't have self ill slot???)

Thanks,

flipside

[Sushidelic]

Hi Flipside!

Nice result! To answer your questions:
1. Irritated is probably not the right word. I was not quite sure if i misunderstood your question, because there was no reply directly mentioning cameramapping in max so far.
2. You shouldn't use a vray material for this, because as you said, it has no self illumination. The light you need is already in your photograph you mapped onto geometry, so no need to recieve shadows or light, as long as it is not directly interacting with additional cg objects in your scene. There you'll need a matte material to catch your shadows/reflection placed a little above the surface normal.

Greetings, Michael

[GoncaloP]

Great

[flipside]

Thanks sushidelic!

So in this scene:



(tabletop and some objects on it are modeled, rest is bg pic)

Here I camera mapped the tabletop, but just in a vray material diffuse slot. There are objects on top of it and they seem to cast shadows onto the table. But according to your explanation, you would do it differently?

If I make the tabletop a matte/shadow material (with vraymtlwrapper), then the reflections of it have the color of the diffuse slot that's inside the mtlwrappermaterial. I'm not sure what you mean with the use of the matte shadow material. It seems to be working the way I do it now. Are there any disadvantages to my technique?

Thanks for any info!

regards,

flipside[img][/img]