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"Combo Images"
When a lateral photograph and a lateral radiograph have been entered
in the Metron database on the same date for the same animal, Metron
can automatically create an image which combines the two. Likewise,
when a solar photo and a 60-deg DV radiograph have been entered,
a "combo image" created from those two acn be created.
In the case of this solar combo, we also require that a lateral
radiograph be present, as it is used to know how high in the capsule
the P3 bone is, as well as it's orientation.
How it works: From the scale factors entered, and from the picks
done during "Guided Mark-Up", Metron knows how to put
the images together. In the case of the solar combo image, Metron
has to use special mathematical transformations to create an accurate
resulting image -- this is because the 60-deg DV radiograph is taken
at (approx) 60-degrees. Due to this fact, one part of Metron's algorithm
for combining the images is a special "warping" of the
radiograph to compensate for how it was taken and to make it ready
to be overlaid on the photo.
Here's what Metron does automatically when creating the lateral
combo image: First, both images are rotated slightly to ensure that
the 'ground level' line is perfectly horizontal. Next, one image
is expanded or shrunk so that it's scale (pixels per inch) matches
the second image. Next, the first pick (near the toe) of the dorsal
hoof wall from each image are made to lie on top of each other by
shifting the images in X and Y as needed. Finally, a special masking
technique is used to allow the radiograph image to "come thru"
the photograph in the central area near the bones - but as you move
away from the bones, the image fades back to the photograph.
To get the most dramatic results, you need to start with two good
images. For this purpose, nothing beats a well-taken image on good
equipment, but the MEGA (now in Metron 4.0)
can help enhance the radiograph. It also is very important that
both be scaled properly, and for this purpose the "EponaTech
Block" is highly recommended. Finally, it is important
that the "ground level' was picked correctly in both images,
and that the pick near the toe of the dorsal hoof wall was done
in the same way for both images.
Here are some examples. In each case, if you click on the small
image, you will see an enlarged image.
Toe too long!
Metal shoe with wedge pad
Plastic shoe glued and nailed on
Solar combo image
If you already have Metron-PX, upgrading to version
4.0 will get you the ability to create the solar combo image as
well as the lateral combo image.
All the new features in Metron-PX 4.0 are described here.
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