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DELFTship tutorial – Using background images
DELFTship
DELFTship tutorial – Using background images
Description
By using scanned images of an existing linesplan it is shown how a 3D DELFTship model can be created
using background images. The linesplan used for this tutorial is from an old motorboat. It's a hard chined
motorboat with slightly curved sides at the stern.
During this tutorial also a lot of the basics will be
explained. You'll be shown how to
• Create knuckle lines
• Use background images
• Assign control curves
• Fair control curves by moving points with the
mouse
• Move points with the cursor keys.
Illustration 1 : Linesplan used for this tutorial
: Linesplan used for this tutorial
• Add new faces manually
• Insert new points
• Insert new edges
• Add new layers
• Select faces
• Assign faces to a different layer
• Add stations
• Make a curved transom that ends perpendicular to the centerplane of the hull
1. Start a new model
Description
Action
Start a new model
Select File => New from the
mainmenu
The window from illustration 2
appears. Fill in the appropriate
numbers.
Illustration 2 : New model window.
: New model window.
Illustration
Illustration
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DELFTship tutorial – Using background images
DELFTship
2. Creating knuckle lines
Description
Action
The default hull is a round
bottomed sailing boat. The
linesplan we're trying to
reproduce is a hard chined
motorboat. The first thing we're
going to do is create a knuckle
line that is going to be the
chine of our motorboat
Select the edges as shown in image 3.
You can select them one by one by
clicking on each edge with the left
mouse button. An easier and faster
way is to select just one edge while
keeping the Ctrl key on your keyboard
pressed. DELFTship automatically
traces and selects the connected
edges.
Turn the normal edges into
knuckle (crease) edges.
DELFTship draws crease
edges in red.
Select Edit => Edge => Crease from
the mainmenu.
Illustration 3 : Creating a knuckle line.
: Creating a knuckle line.
3. Inserting background images
Description
Action
DELFTship has three different
views on your model
• Plan (top) view
• Profile (side) view
• Bodyplan (front)
view
• Perspective (view).
Select the window showing the profile
view. If no such window is available
select a random one and set the view
to profile view. This is done by
pressing the right mouse button
somewhere in the window area. A pop-
up menu appears. Select View =>
Profile .
Call the pop-up menu again and select
Background image => Load . This
opens the file browser. Select the file
you want to use for a background
image.
You can assign a different
background image to each of
these vies, except for the
perspective view
4. Moving a background image
Description
Action
The background image is now
inserted into your model. Every
time you select the profile view
this image will be shown on the
background. In most cases the
background image is not yet on
the right location immediately
after the import. We're going to
drag it to the correct place now.
Select Background image => Origin
from the pop-up menu.
The cursor now changes to a cross
with a big O indication you're going to
change the origin. Press the left
mouse button somewhere on the
background image and keep it pressed
down. If you move the mouse around
now you'll notice the background
image being dragged around as well. If
you release the mouse button again
the viewport will resume to normal
operation.
Drag the image to the correct location.
In this case the lowest point of the
skeg should coincide with the baseline
of your model (Z=0.0). The aft part of
the transom should coincide with the
aft perpendicular (X=0.0).
2
Illustration
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DELFTship tutorial – Using background images
DELFTship
5. Changing the scale of a background image
Description
Action
Select Background image => Set
scale from the pop-up menu. The
cursor changes to a ruler to indicate
you're changing the scale of the
image. Now click on a point of the
background image of which you know
the exact coordinates. The further this
point is away from the origin the better.
Once a point has been selected
another window shows up prompting
for the coordinates of the selected
point. Enter the correct coordinates in
this point and close the window.
In our example the coordinate of the
uppermost point of the bow is 6.75,
1.64
Important: All new background images will automatically have the
same scale applied as this one. This is particularly convenient if you're
importing multiple background images originating from the same
linesplan. So make sure you set the correct scale before importing the
next background image! In our case we import the same image three
times (once for each view) so having exactly the same scale for each
image is crucial.
6. Setting transparency of the background image
Description
Action
Select Background image =>
Transparent color from the pop-up
menu. Click on a spot of your
background image with the color you
want removed. The background image
will now be redrawn in transparent
mode.
If you find the image still too dominant
try blending it with the background.
Use the Background image =>
Blending option from the pop-up
menu and move the slide bar until
you're satisfied.
Note: You can remove transparency again by repeating this process.
Instead of clicking on a spot within the background image simply select
a point outside the image.
7. Adjusting the transparency tolerance
Description
Action
Especially when using
compressed images like jpeg
areas that appear white can
consist out of many shades of
white. In that case if the
transparent color has been set
to white a lot of “nearly white”
noise remains visible. By
increasing the tolerance you
can remove that noise.
Select Background image =>
Tolerance from the pop-up menu.
Experiment a bit with the value until
you're satisfied with the appearance of
the background image. For most jpeg
images a tolerance of 35 works fine.
The higher the compression rate of the
file, the higher the tolerance needs to
be.
3
Once the background image is
on the correct spot we still have
to scale it to the correct
dimensions.
Background images with large
white areas, as is often the
case with a linesplan, can be
very dominant. You can avoid
this by assigning a transparent
color. Areas with the
transparent color will not be
drawn on your screen. In case
of a black and white linesplan
only the black lines will remain
visible.
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DELFTship tutorial – Using background images
DELFTship
8. Importing more images
Description
Repeat this process for the
bodyplan and plan view of your
model.
9. Assigning control curves
Description
Action
Now we're going to assign a
control curve to the deckline.
This control curve is going to
be used at a later stage to:
1) Match the shape of
the deckline of the
background images
2) Fair the deckline in
such a way that we
end up with a very
smooth curve.
Select all of the edges from the
deckline (see also step 2).
From the main menu select Edit =>
Curve => New .
A blue curve is now visible. It is better
visible if you hide the control net. You
can do this by selecting Display =>
Control net from the main menu. If the
curve is still not visible select Display
=> Control curves to turn of the
display of the control curves.
Repeat this to add a control curve to
the chine we've created in step 2.
Add a control curve to the contourline.
Select all edges on the centerplane of
the ship, including the edges of the
bow.
4
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DELFTship tutorial – Using background images
DELFTship
10. Adding the other control curves
Description
If you've added all three
control curves your model
should look something like this.
11. Shaping the deckline
Description
Action
The first thing we're going to
do is to try to match our
deckline to that of the
background image.
Turn of the control net (see step 9).
Choose the plan view and select the
deckline. Once the deckline is selected
the controlpoints and edges used for
this curve will be shown together with
the curvature plot (the purple lines). If
the curvature plot is not visible there
are two possibilities:
1) The display of curvature
plots is disabled. Check (or
enable) it by selecting
Display => Curvature from
the mainmenu.
2) The scale of the curvature
plot is too small to be seen.
You can increase or
decrease the scale by
pressing F10 or F9.
Illustration 4 : Deckline before.
: Deckline before.
Modifying the shape is done by
selecting a controlpoint of the
curve and dragging it to
another location.
Move the controlpoints with the mouse
to their new locations. Start with the
startpoint and endpoint. Then move
the interior points of the curve. If the
deckline is roughly similar to that of the
background image check your
curvature plot. Make sure the
curvature changes gradually along the
curve. If not then adjust the
controlpoints nearest to the curvature
peaks or valleys. Try to distribute the
points evenly along the curve
Illustration 5 : Deckline modified to match the background image.
: Deckline modified to match the background image.
5
Illustration
Illustration
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