Author: Looniper
Tools Needed

• Poser
  

Introduction


If you have ever used the Group Edit tool in Poser, you have seen the Create Perspective UVs button, but probably had no idea what it was for.
Even if you pressed it out of curiosity, it likely had no noticable effect unless certain criteria were already met.
This tutorial will step you through creating a Perspective UV projection on a box, and will go on to explain how to apply this tool to the creation of working lenses.
Note: None of the images in this tutorial have been postworked. They all represent exacty the effect you should get when following the steps indicated.
[You must be registered and logged in to see this image.]

Step 1 - concept


Create Perspective UVs (hereafter simply CPUV) changes the mapping of a selection of polygons to simulate a projection of their texture map from the current camera view onto the environment.
Don't worry, doing it is much easier than understanding it.
In simpler terms, this means that with the right texture map, an area of an object can be made to appear as if it were a hole in the object, or an entire object can look as if it were made from glass. Neither of these requiring the use of any transparencies.

Step 2 - setup


You do not need to have a background image loaded to use CPUV, but for this tutorial it is important.
The image you use is up to you. I am using a simple render of Victoria 3 (pe036) with the hi-res universal textures (tx307) and Wild and Messy hair (ac420) over a sky created in Vue d'Esprit 4.
[You must be registered and logged in to see this image.]
With the background image loaded, it is time to bring in a victim in which to punch some holes.
Change to the Front camera and load a box from the props library.
Scale box_1 to about 500% so that it covers a fair amount of the background.
You should have something like this.
[You must be registered and logged in to see this image.]

Step 3 - grouping


With the box selected, click on the Grouping Edit tool icon.
A detailed explanation of the Grouping Edit tool is beyond the scope of this tutorial, but for those unfamiliar with its use, I will explain enough to use it for our purposes.
Click the Create Group button and enter the name Holes.
Now select a few areas on the box that will become the holes. Selected parts display as red with the rest as black. If you select an unwanted area, simply hold Ctrl and select the undesired portions to remove them.
[You must be registered and logged in to see this image.]
For CPUV to work, we need a material name for our holes. Click the Assign Materials button and name our material. Use Holes again to keep things easy.
Now close the Group Edit tool and you will notice that our new Holes material has been given a random color. The color will vary but is unimportant because we will be changing it regardless.
[You must be registered and logged in to see this image.]

Step 4 - Punching Holes


With the box selected, go to Render - Materials and change the Holes material's Object Color to white. For its texture map, load the same image you are using as the background picture.
If you have followed the steps up to this point, your box should now resemble this.
[You must be registered and logged in to see this image.]
Now it is time to see what CPUV can do.
With the box selected, click on the Group Edit tool, click the CPUV button and close the tool again.
Now our box has holes in it!
[You must be registered and logged in to see this image.]
Well not holes precisely.
If you change the camera viewing angle, you will quickly get a better understanding of what you have just done.
The mapping is generated as a path directly from the camera view to the background, so any change in viewing angle will break the illusion of the holes.
Of course, there are other purposes for this tool. Imagine making the rest of the box transparent, making multiple boxes similarly mapped, and positioning them as if in layers. The effects can be impressive.

Step 5 - Lens Methodology


You've seen the most basic application of CPUV, so let us explore one of its more advanced applications, the creation of functioning lenses in Poser by simulating refraction.
Refraction is a change in the direction of light when it passes through a curved survace.
In the case of a simple convex lens (such as a magnifying glass) it causes light to project outward, making objects appear larger.
By the same physics, light passing through a concave lens will project inward, making objects appear smaller.
For this tutorial, you do not need to understand refraction, but the more you understand it the more creative you can be with lenses. Producing both lens types on the same surface for example.
Let us begin by creating our lens.

Step 6 - Building the Lens


Since CPUV will map an object to show a direct line from our view to the background, we need a way to stretch that mapping in order to act as a lens. The easiest way to do this is using Poser's Magnets.
Since magnets are another topic beyond the scope of this tutorial, I will give exact values on placement and dials to create the lens.
Load the background image into a fresh scene and change to the Front view again, this time changing the display mode to Wireframe.
Load a ball from the props library and be sure its Ytran and Ztran dials are set to 0.000.
Scale it up to 500% as we did with the box above.
With the ball selected, on the menu chose Object - Create Magnet. The scene should now look like this.
[You must be registered and logged in to see this image.]
Using the list under the workspace image, select Props and chose MagZone_1.
We want to deform only the end of the ball so we need to move the MagZone_1 and MagBase_1.
Xtram and Ytram 0.050 for each of them.
With those moved to the correct positions, chose Mag_1 from the list and increase its Scale to 150%.
Select the ball again and go to the Object menu and Spawn Morph Target, giving it the name Zoom.
Delete the Magnet prop since it is no longer needed.

Step 7 - Making the Lens Work


You may have noticed that the ball faces to the side rather than toward us.
We want it to face us now so adjust its YRotate dial to -90.
With the ball selected click on the Group Edit tool and create a new group called Lens.
Since we are using the entire ball, we don't need to select anything, simply click Add All and press the CPUV button and close the Group Edit too.
Now under Render - Materials, set the ball's Preview material's Object Color to white (it should be already) and its Texture Map to the same image as the background.
The Highlight and Reflective Colors should both be set to black.
At this point, our ball-lens appears simply as a glass plate in front of the background.
[You must be registered and logged in to see this image.]
Use the Zoom morph dial we created to simulate refraction.
Congratulations! You have just created a functioning lens in Poser.
You can adjust the Zoom dial higher to zoom in, and lower to zoom out.
[You must be registered and logged in to see this image.]
If you apply too much Zoom either way, the morph will cause the ball to expand or twist in on itself, so keep the values low for this lens.
For more Zoom-In, have the Zoom dial set to less than 0 when you use the CPUV button.
For more Zoom-Out, have the Zoom dial set to greater than 0 when you use the CPUV button.

Step 8 - Changing the Lens


Changing the lens to focus on a new location is simple.
Be sure the Zoom dial is set to 0 and drag the lens over the point you wish to magnify.
Once positioned, open the Group Edit tool and press the CPUV button to update the mapping.
You may wonder why we morphed the ball sideways and then turned it to face us.
This is for 2 reasons.
First, since we wanted a round lens, creating this morph on the side of the ball would have made the edges look blocky because of the flat edges facing the camera.
Second, in wireframe view the lines of the ball come together to form a point which we can use to position the lens with some precision.

Step 9 - Experiment


Don't feel limited to just the material given here.
With the correct application, CPUV can create Funhouse Mirrors, accurately refract a scene through a crystal ball, and any number of other effects.
I hope you find this tutorial useful.
~Looniper]