User:Owenpsmith/Preparing drawings for modelling: Difference between revisions

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User:Owenpsmith/Preparing drawings for modelling (view source)

Revision as of 02:59, 25 August 2018

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The nose of the aircraft should be pointing to the left, if it is not then rotate it using Image -> Transform menu.
The nose of the aircraft should be pointing to the left, if it is not then rotate it using Image -> Transform menu.


We will now ensure the drawing is square and symmetrical.  Duplicate the layer and set the transparency of the top layer to 50%.  Flip the top layer and move it so that the center line of the top view lines up with that of the bottom layer.  Fine tune the position of the top layer until it most closely matches the bottom layer.  In this case it is pretty close, but there is some slight blurring on the outer wings and tips of the horizontal stabilizers, but it is pretty square overall.  Since it is close, I will use this image as is with both layers showing, and I will run the outline of my model down the middle of the lines where there is some slight blurring.  We can merge these two layers together now to simplify things later.
We will now ensure the drawing is square and symmetrical.  Duplicate the layer and set the opacity of the top layer to 50%.  Flip the top layer and move it so that the center line of the top view lines up with that of the bottom layer.  Fine tune the position of the top layer until it most closely matches the bottom layer.  In this case it is pretty close, but there is some slight blurring on the outer wings and tips of the horizontal stabilizers, but it is pretty square overall.  Since it is close, I will use this image as is with both layers showing, and I will run the outline of my model down the middle of the lines where there is some slight blurring.  We can merge these two layers together now to simplify things later.


[[File:Tutorial104.jpg|thumb|none|800px|]]
[[File:Tutorial104.jpg|thumb|none|800px|]]


Next we will check for accuracy of the drawings by comparing it to a reference photo.   
Next we will check for accuracy of the drawings by comparing it to a reference photo.   
Open the reference photo as a new layer on top of the drawing layers and set its transparency to 50%.  Scale and move the image until its outline lines up with that of the drawing.  Note that all photos will have some perspective distortions and parallax, so not all misalignments with a reference photo are bad.  
Open the reference photo as a new layer on top of the drawing layers and set its opacity to 50%.  Scale and move the image until its outline lines up with that of the drawing.  Note that all photos will have some perspective distortions and parallax, so not all misalignments with a reference photo are bad.  


[[File:Tutorial105.jpg|thumb|none|800px|]]
[[File:Tutorial105.jpg|thumb|none|800px|]]
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We will process the front view similarly to the top view, with a symmetry and reference image check, but like the side view we won't worry too much about height.  I'm really only including the front view in the tutorial because it has some major inaccuracies that we will fix in the scan itself.   
We will process the front view similarly to the top view, with a symmetry and reference image check, but like the side view we won't worry too much about height.  I'm really only including the front view in the tutorial because it has some major inaccuracies that we will fix in the scan itself.   


This is the drawing after I have straightened it and added a reference image as a new 50% transparent layer on top.  As you can see the wings have waaaay too much dihedral.  I didn't need a reference image to know the dihedral was a bit off, but it will help us set it straight (so to speak).
This is the drawing after I have straightened it and added a reference image as a new layer with 50% opacity on top.  As you can see the wings have waaaay too much dihedral.  I didn't need a reference image to know the dihedral was a bit off, but it will help us set it straight (so to speak).


[[File:Tutorial112.jpg|thumb|none|800px|]]
[[File:Tutorial112.jpg|thumb|none|800px|]]
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[[File:Tutorial115.jpg|thumb|none|800px|]]
[[File:Tutorial115.jpg|thumb|none|800px|]]
== Cross sections ==
I will do one cross section as an example, the others can be added similarly.  The plans I have been using so far have very basic "outer skin" cross sections, but I also have some from the maintenance manual that show the internals.  The one problem is that they were photographed rather than scanned, so there is a good possibility they have some perspective issues. 
[[File:Tutorial116.jpg|thumb|none|800px|]]
The darker portion of the image was not sitting as flat as the lighter section, so we will work from the lighter section as it will have less distortion.  Use the rectangle select tool to select the left half of the cross section, up to the center line.  Copy it, paste it as a new layer, then flip it horizontally.  Move it over to the right side and line it up on the center line.  By setting the opacity to 50%, we can see that the new layer extends significantly past the original lines for the right side.  This is due to the paper not being flat, but we have fixed it now by using the better copy from the other side. 
[[File:Tutorial117.jpg|thumb|none|800px|]]
Set the opacity back to 100% and merge the layers.  Crop the image tightly to the edges of the cross section and we're done.  The aspect ratio may not be perfect, but we will look at that once we import it into AC3D.
[[File:Tutorial117.jpg|thumb|none|800px|]]
. . and we're done!  Please see my next tutorial to see how I use these drawings in AC3D.
Owenpsmith
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