ImageModeler 3.5 is an
application designed to create 3D models -- fully textured
-- from a series of photographs. This type of technology is
not new or unique to ImageModeler.
Interstudio's DigiCAD is a similar application more focused
on architectural photogrammetry than ImageModeler, but certainly
this program is well built for that pursuit as well.
ImageModeler for X
ImageModeler is a fully native Mac
OS X application. The interface is fully Aqua compliant
and quite handsome in appearance. The main window features
a tabbed interface over the display area (3D workspace area).
This tab structure directly reflects the actual "workflow"
for working in ImageModeler. You start your project by "loading
images" (the first tab on the left). Then you move on to "calibration",
"measurement", "modeling", "texturing" and eventually to "export".
As you move through this workflow (tabs) under the tab bar
area are tool buttons unique to the particular process you
are in (eg: calibration). A Tools Properties dialog box sits
on top of the Scene Browser (all to the right of the display
Below the display area consists of Display Settings
and the Assistant palette -- a palette which provides direction
for using each tool. (see images 001
- 002) Because of the complexity of the calibration,
measurement, and modeling of data -- all over photographic
images -- ImageModeler provides a fully customizable colors
preferences for all of the lines, markers and axis you will
utilize in the display area. As a side note, we also advise
that you do not use black & white photographs unless the subject
is simple and of definite contrasting values. Color simply
helps in the placement of markers during calibration.
ImageModeler is not an easy application to learn.
It is not as easy to figure out as say an Apple iApp like
iMovie or iPhoto, yet it is somewhere between there and an
application like Final Cut Pro or formZ. Having the Assistant
Palette was a godsend in a number of "not-so-obvious" situations.
Even then, occasionally the application was difficult to figure
out. A specific instance of this is setting the "world space"
axis using the program's tools to do this. Overall the application
has a reasonable learning curve, but if you buy the program
for a photogrammetry or modeling project of a complex shape,
plan on giving yourself a few weeks to master the program
and work out "trial-and-errors" in your project photography.
The Essentials: Mastering the Photography
When working with the program we learned the hard way that
you must take the correct photographs in order for calibration
to have a chance at being successful. Because trees often
block the views of buildings, they can also block the view
of specific "ideal" locations on the building for the placement
of markers (more on that in a minute). ImageModeler's documentation
discusses this subject, but its own tutorial of a simple building
with aerial photography misrepresents the true difficulty
of photographing a more complicated building in preparation
for ImageModeler work.
Once you have taken good pictures the process of bringing
them into ImageModeler is very straight forward. You have
the ability to load images and to specify the camera's technical
characteristics (focal length for instance) (see
images 003-004) If you have to shoot a building with
different lens (say a 24mm wide angle and a 50mm lens) you
can specify which images are shot with which lens. This helps
the calibration process.
When your images are loaded you spend time locating "markers"
on the images. These markers are called "locators". It is
best to place each marker (1-n) in every photograph if possible
but many times that will not be possible. In that case place
markers in at least three images if possible. We are not sure
how meaningful it is to place a marker in just two images.
In our most complex building undertaken, we placed over 20
markers (see images 001-002).
This process can take some time. Placing markers is actually
kind of fun. Using the Place Marker tool you click on an image
and a small zoom window appears under the cursor point, enabling
you to place the marker accurately down to the pixel. (See
image 005). It takes some thoughtfulness to decide
which points to place markers at, for you will use these markers
turned 3D locators as snap points for modeling later. Hence,
the trial-and-error of the process will inform your photography
skills for the next ImageModeler project you undertake.
As you place your 2D markers they become 3D locators in the
3D display model space. At a certain point ImageModeler will
have enough markers/locators to automatically calibrate the
scene. When this happens it becomes optional to place further
markers but you will likely do so for modeling purposes. Again,
as you will see, you use locator points for snapping guides
when you do your modeling work.
Next Page: Modeling,
Texturing and More
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