and, therefore, will not align correctly. Select the data you wish to exclude with
Select Region
.
Then, after you select
2:Calc Fit,
you will be asked “Would you like to exclude the selected
region from the alignment process?” If you have more than one region selected you will be
asked for each region individually.
Note: This excludes regions from the alignment calculation – but not from the
alignment. The alignment is applied to the entire file.
3: Apply Fit
Next, select
3:Apply Fit
. This makes the unaligned range file aligned, which makes it possible to
make measurements between points in this file and points in the other aligned files. Note that
this does not change the data in any way – it merely associates an alignment with the data.
When you save the scene file you also save the alignment.
Info
The
Info
button provides the error measurement if you wish to refer back to it.
Show
The
Show
function creates a model. It takes the two range data files (the file you’re aligning to,
and the newly aligned file), creates a triangle mesh of the points in each file, and then combines
the two into a single VRML data model. If the range files have color the model will also have
color.
To create this model, the program ‘decimates’ the number of points in the range data – it
reduces them by choosing every third, fourth, or nth point. If every point were used in creating
the triangle mesh, the resulting model would be too large to view interactively on a PC. The
amount of decimation is determined by the value of the
Target Triangles in Model
parameter in
the
Preferences
function of the
File
menu. The model created is a ‘texture-mapped’ VRML file.
Note: Point decimation produces a model very rapidly, but also significantly
reduces the amount of detail in the data. Model simplification, which requires
significant compute time, produces a higher quality model. Model simplification
is discussed in section 11.4.
Note: After creating the model file you’ll notice an asterisk (*) next to the file
name in the window border. This means that you must save the file if you would
like to keep it in the scene.
Once range files are aligned you can create 3D models from all or parts of any number of
aligned files at any time. This is discussed in section 11.
If you would like to undo the Apply function and edit the points, go to the Edit menu and
choose
Align
->
Clear Alignment
. You can also edit the points and choose Calc and Apply to
overwrite the previous alignment.
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