AECbytes Tips and Tricks Issue
#18 (May 30, 2007)
Perspective Matching in Photoshop CS3 Extended
Book & Video Author
Adobe unveiled its Creative Suite 3 this month
and with it comes a much-improved "Photoshop
Family," whose members include: Photoshop
Album Starter Edition (baby), Photoshop Elements
(the kid), Photoshop (mama), and Photoshop Extended
(big daddy). These range in price from free to
US$999. Photoshop Extended has some great new
features for us in AEC, including 3D layers and
Enhanced Vanishing Point. In this issue, I'll
show you how 3D layers alone make Photoshop Extended
worth the extra upgrade.
3D layers allow you to manipulate geometry and
edit its dependent texture maps very conveniently
inside Photoshop. This feature makes it
easy to integrate a 3D model of a virtual building
with 2D photographic imagery of its real-world
site. The integration of real with virtual is
known as perspective matching.
In this tutorial, I will begin in SketchUp 6
Pro with a 3D model (download the sample files
You can use almost any 3D program to make your
model and export it to an exchange format. This
simple model has two materials with texture maps
assigned to the geometrysiding and roofing.
The clerestory windows and door are flat colors.
In SketchUp Pro, choose File
> Export > 3D Model.
In the Export Model dialog box,
open the Export Type drop down
and select Collada (*.dae). Collada
is the hot new digital asset
exchange format that's built
for the future (exporter
available for 3ds Max). Note that many other legacy
and proprietary 3D formats are also available
for export in SketchUp Pro.
Click the Options button and
make sure that Export Texture Maps
is checked. Navigate to a memorable folder (such
as the desktop), name the file Villa.dae,
and click the Export button.
Notice that a Villa subfolder was automatically
created on your hard driveit contains the
exported 3D model's texture maps (in this case
two .jpg files). You may now quit SketchUp Pro.
Launch Photoshop CS3 Extended
and open the SitePhoto.jpg sample
file. This particular photo was taken in Tuscany,
where I like to imagine this tutorial's hypothetical
building site to exist (at the top of the hill).
Immediately resave the image as PerspectiveMatching.psd.
Hold down the Alt key and double
click the background layer in the Layers
palette to convert it to a regular layer. Rename
Layer 0 to Site Photo.
Choose Layer > 3D
Layers > New Layer from 3D
File. Open the Files of Type
drop down and select Collada (*.DAE).
Your 3D program must export to one of the formats
shown in this drop down if you are to get it into
Photoshop. Navigate to the desktop and select
the Villa.dae file you had saved
Click the Open button. After
a few moments, you'll see a Rendering progress
bar and when it's done the 3D layer will appear
in the document window. Notice the layer thumbnail
has a little cube icon indicating that it is a
3D layer. Also, the two texture maps appear as
dependents underneath the layer, almost as if
they were layer styles. In fact, each texture
acts like a smart objectyou'll read more
on that later.
Double click the Villa layer thumbnail
to "open" the 3D layer for editing.
The Options bar then displays
tools for 3D navigation:
Make the building smaller by dragging the Slide
tool upward in the document window. Rotate
and Roll the building to match
the perspective of the site photo. It's not an
exact sciencejust make it look right. Drag
the building down and anchor it to the earth.
Click the Commit button at the
extreme right side of the Options
bar when you're happy with the building's location
on site. The building will now be treated as 2D
pixels, but you can always reopen the 3D layer
for editing, should you wish to reposition or
reorient it with respect to the site photo.
At this point I have to say that the building
is too dark. Thankfully, there's no need to worry
about complex materials, photometric lights, and
rendering parameters in Photoshop (like you do
in most 3D software). Let's make some quick adjustments,
Add a Brightness/Contrast adjustment
layer by clicking the middle icon at
the bottom of the Layers palette.
Drag the brightness slider up
to +100% to make the very dark
building look brighter. Click OK
to close the Brightness/Contrast
Unfortunately the adjustment layer has brightened
the Site Photo Layer too, making
the site appear way too bright. No problem, create
a clipping mask so that the adjustment layer affects
the Villa layer alone.
Hold down the Alt key and move
the cursor in between the Brightness/Contrast
adjustment layer and the Villa
3D layer. You'll see the cursor change
to the clipping mask icon. Click with the clipping
mask cursor and the adjustment layer gets indented
with a downward facing arrownow it adjusts
the Villa layer
Since the Villa layer
is on top of the Site Photo layer,
the virtual building completely obscures
the real site. Some of the real site should show
in front of the building. In particular, there
are some trees and shrubs in the Site
Photo layer that I'd like to reveal.
This is easily accomplished with a layer mask.
Target the Villa layer
and click the Layer Mask icon
(third from the left at the bottom of the Layers
palette). A new thumbnail appears to the right
of the Villa's 3D layer icon. A link icon appears
between the layer and its mask.
Target the Villa layer
mask and press D to set the default
colors, and then press X to swap
black into the foreground. Select the paintbrush
tool by pressing B. Change the
brush size by pressing the left and right square
bracket keys repeatedly. Change the brush hardness
by holding Shift and pressing
these keys. Select a small soft brush. Paint away
portions of the building to reveal the site. This
is done by painting in black on the Villa
There is a cypress tree that pokes up above the
roof that I'd like to cut downI'll consider
this to be on the building footprint. This tree
is on the Site Photo layer so
painting on the Villa layer
mask isn't going to work. Target the Site
Photo layer. Select the Clone
Stamp tool by pressing S.
Hold down the Alt key and click
somewhere close to but just above the roof in
the blue sky. This is the area you will be cloning.
Click multiple times on the offending tree to
stamp it out.
Let's say that you're not happy with the siding
color. Now you can easily experiment with siding
color options in the context of the actual site.
Double click the Cladding_Siding_Tan texture
nested below the Villa 3D layer.
Much like a smart layer, the texture map that
originated in SketchUp opens in the form of a
temporary .psb file. You have access to this file's
layers, which right now shows only a Background
Add a Hue/Saturation adjustment
layer. Set the Hue to +34
and the Saturation to
-40 and click OK
to close the Hue/Saturation dialog
box. Click the texture's close box and choose
Yes when prompted to save the
texture file. The siding color updates in the
Adjusting textures couldn't be any easier.
The last thing I'll do is show you how a layer
style can be used to shade the building. Target
the Villa 3D layer and click
the Effects button (second icon
from the left at the bottom of the Layers
palette). Choose Gradient Overlay
from the pop-up menu and the Layer Style
dialog box appears.
Choose a black and white gradient if it's not
already selected. Change Style
to Linear, Angle
to 33 degrees, Scale
to 150%, Blend Mode
to Multiply, and Opacity
to 33%. Drag the gradient to
the left in the document window so only the left
side of the building appears darker. Click OK.
Notice how the Layers palette
now organizes a great deal of information. In
summary, the adjustment layer was clipped to affect
only the Villa layer. The Villa
layer is 3D and can be opened for navigation
by double-clicking its thumbnail.
The Villa layer mask hides portions
of the 3D building. The Site Photo layer
was cloned and stamped to hide any unwanted content
upon integration with the virtual model. Effects
and textures are nested under the Villa
layer and can be easily edited by double-clicking
on the appropriate row. Textures are smart and
can each contain adjustment layersremember
these are not visible in the main document Layer
This brings me to the end of this tutorialI
hope you enjoy 3d layers in Photoshop CS3 Extended
as much as I do. A video showing this technique
is available on my video podcast, The
About the Author
Scott Onstott is a book and video author of
AEC software tutorials. He has a degree in architecture
from UC Berkeley and has served as an instructor
there, in addition to working in several prominent
engineering, architecture, and interiors firms
in San Francisco. He has also worked as a technical
editor and technology consultant.
Scott has contributed to over two dozen books
and videos on AutoCAD, Architectural Desktop,
VIZ Render, Revit, 3ds Max, VIZ, Photoshop, Illustrator,
Painter, Fireworks, and Dreamweaver. He most recently
with Lynn Allen. He can be reached via: www.ScottOnstott.com.
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