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User:Owenpsmith/Preparing drawings for modelling (view source)
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===== This tutorial explains the steps I use to prepare scanned drawings in Gimp for use in building an aircraft model. ===== | ===== This tutorial explains the steps I use to prepare scanned drawings in Gimp for use in building an aircraft model in AC3D. ===== | ||
Good quality models start with good quality drawings, but even the best drawings have issues. Some are not 100% accurate or do not represent production specs, or are not quite square. Even if they are absolutely perfect, issues can be introduced during scanning. Despite our greatest attempts to scan them straight, they are never 100% perfect. I use the following steps to ensure my drawings give me a solid start on my model, to reduce issues later on and improve overall accuracy. | Good quality models start with good quality drawings, but even the best drawings have issues. Some are not 100% accurate or do not represent production specs, or are not quite square or symmetrical. Even if they are absolutely perfect, issues can be introduced during scanning. Despite our greatest attempts to scan them straight, they are never 100% perfect. I use the following steps to ensure my drawings give me a solid start on my model, to reduce issues later on and improve overall accuracy. | ||
I will be using the development of the Canadair Tutor for this tutorial (how appropriate). I use Gimp for my graphics work, but the general techniques can be used in any photo editing software. As this is not a Gimp tutorial and you may be using your own software, I will not go into details on the Gimp interface. If you are using Gimp, I have installed the | I will be using the development of the Canadair Tutor for this tutorial (how appropriate!). I use Gimp for my graphics work, but the general techniques can be used in any photo editing software. As this is not a Gimp tutorial and you may be using your own software, I will not go into details on the Gimp interface except where I feel it is necessary. If you are using Gimp, I have installed the Straighten and Crop plugin. I am starting with some scanned 3-view drawings with cross sections, and some reference photos that are roughly orthogonal. | ||
== Top View == | == Top View == | ||
We will start with the top view | We will start with the top view since length and wing span are more precise than height: | ||
[[File:Tutorial101.jpg|thumb|none|800px| | [[File:Tutorial101.jpg|thumb|none|800px|]] | ||
In this case the top view is at 45° on the sheet, but even if it is "straight" we will still try to straighten it perfectly in this step. | In this case the top view is at 45° on the sheet, but even if it is "straight" we will still try to straighten it perfectly in this step. | ||
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Select the Path tool and click on a point at each end of the marked center line. | Select the Path tool and click on a point at each end of the marked center line. | ||
[[File:Tutorial102.jpg|thumb|none|800px| | [[File:Tutorial102.jpg|thumb|none|800px|]] | ||
Zoom in and place each end of the path more precisely. | Zoom in and place each end of the path more precisely. | ||
[[File:Tutorial103.jpg|thumb|none|800px| | [[File:Tutorial103.jpg|thumb|none|800px|]] | ||
Select Tools -> Transform Tools -> Straighten and Crop. If it is a 45° rotation, set Crop after rotating to "No crop". Click "Ok" | Select Tools -> Transform Tools -> Straighten and Crop. If it is a 45° rotation, set Crop after rotating to "No crop". Click "Ok" | ||
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We will now ensure the drawing is square. 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, 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. 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, 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. | 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. | ||
[[File:Tutorial105.jpg|thumb|none|800px| | [[File:Tutorial105.jpg|thumb|none|800px|]] | ||
We can see now that there are some inaccuracies in the engine inlet areas, as well as the very front of the nose. I will leave this photo in as a layer in the master but will hide it when I save a jpg for use in AC3D. I will include the layer again later when I am working on these areas. | We can see now that there are some inaccuracies in the engine inlet areas, as well as the very front of the nose. I will leave this photo in as a layer in the master but will hide it when I save a jpg for use in AC3D. I will include the layer again later when I am working on these areas. | ||
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We can now crop the drawing to the very edge of the model and clean up extraneous drawings, but be sure to leave in any cross-section references. When cropping, use the select tool with the aspect ration option set to the aspect ratio of the aircraft base on documented aircraft dimension. In this case you can see that this results in the aircraft length being a bit short, but this can be explained by the drawing having a stubbier nose that the real aircraft, so we are all good. | We can now crop the drawing to the very edge of the model and clean up extraneous drawings, but be sure to leave in any cross-section references. When cropping, use the select tool with the aspect ration option set to the aspect ratio of the aircraft base on documented aircraft dimension. In this case you can see that this results in the aircraft length being a bit short, but this can be explained by the drawing having a stubbier nose that the real aircraft, so we are all good. | ||
[[File:Tutorial106.jpg|600px| | [[File:Tutorial106.jpg|600px|]] | ||