The views alignment
Dear 3D Photo Friend,
When you shoot for 3D lenticulars you have to shoot the object several times from different angles. That is the reason why your 3D frames have to be aligned by one point. That is the same process when you look at an object by your both eyes. If you want to see an object clearly you have to direct and fokus both of your eyes at the same point.
The process of frames alignment is quite similar. We have to align all frames by one point. If you do not align the frames your lenticular picture will be blur. Today I would like to offer you another article of Eugenia Wassenmiller about frames alignment. In my book "How to make high quality lenticular 3D photos and Flip pictures for home and business" I describe another way. But this way is good too. Let's start!
Let's examine this beautiful stereo pair to find out how the views are aligned:
Stereo pair by Alexandre Dzuba
Stereo photography without special devices, like the Tripod Add-on may cause the following errors:
- incline of one view relatively to the other;
- incline of both stereo views;
- different scale of the views.
The stereo pair we will align in Adobe Photoshop. An alignment has the following steps:
Step 1. Zero point setting;
Step 2. Scaling of the right view against the left view;
Step 3. Rotating of the right view against the left view;
Step 4. Simultaneous rotating of the right and left views;
Step 5. Repeat all steps with higher precision.
Now I am going to describe all steps in details. We will use the Adobe Photoshop software, but the base principles can be used in other graphical software.
1. Zero Point setting
Open the left and right shots in Photoshop. Select, copy, and paste the left image over the right one. You created a two-layered document: the left image is in the lower layer, the right one is in the upper (or vice versa). Now we can rotate, shift, scale our views using the Photoshop tools.
We'll use guides and rulers. If the rulers are not visible, choose View -> Rulers. Drag from the horizontal ruler to create a horizontal guide, and vertical ruler to create a vertical guide. Mark lower layer as visible and upper layer as invisible. Mark the pestle tip using cross guides. Then mark upper layer as visible and shift the pestle tip to the guide crossing. The guide crossing is our zero point.
|lower layer, mark the pestle tip||upper layer, align by zero point|
The first step is finished. Now don't remove the cross guides. We'll use them in the next steps of alignment.
2. Scaling the right view against the left view
The next step calls the scaling. Mark lower layer as visible and upper layer as invisible. Drag the two horisontal guides to mark upper and lower petals. Then mark upper layer as visible. Look at the upper and lower petals, the scale of this image is a little bigger.
|lower layer, mark the upper and lower petals||upper layer, scale by guides|
Set upper layer as active, and a paintbrush icon appears next to the layer in the Layers palette.
Choose View -> Actual pixel to display an image at 100%.
Choose Edit -> Free transform. All transformations are performed around a fixed point called the reference point. By default, this point is at the center of the item you are transforming. However, you can change the reference point or move the center point to a different location. Drag the center point to the our zero point.
To scale numerically, enter percentages in the W and H text boxes in the options bar. Click the link button to maintain the aspect ratio.
Let's go to the next step.
3. Rotating the right view against the left view
We need the second point to rotate the right view against the left view. This point must be located in the plane of zero point. Let's call this plane a zero plane. If the point is located in the zero plane, this point have the same position in both left and right images. The zero point and this second point is used to rotate the view.
Of course, we don't know the location of the second point. We can find it in the following way. Enter "50%" in the Opacity text box from the Layers palette menu. Choose Edit -> Free transform. Drag the center point to our zero point. Rotate the upper layer and find the fragment having the same position in both left and right images. This is the needed fragment and the needed angle of rotating.
It would be better to find the second point as far as possible. In this case we set the rotating angle with high precision.
4. Simultaneous rotating of the right and left views
Now we correct the canvas angle. Enter "50%" in the Opacity text box for the upper layer. Look at the background. The background have observable parallax. Select the Line Tool from the Shape Tool in the toolbox. Draw the lines to connect the identical points in the background of the left and right images. This lines must be in a new layer, this layer will be deleted after the alignment.
Then rotate the right and left views simultaneously. Choose Image -> Rotate Canvas -> Arbitrary.... Enter an angle of 3 degrees, then 1 degree, then 0.5 degree. Rotate until the lines become close to the horizon.
|connect identical points by lines||rotate canvas until the lines become close to horizon|
Now we have to repeat all steps with higher precision. We get these aligned views:
We can't crop this image without loss of a big part of it. But we can make a carved frame:
This stereo image is better than the first variant.
© Eugenia Wassenmiller
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