A JPEG Image Found in an Internet Search

A JPEG Image Found in an Internet Search

In Country Style Cabinets with a Furniture Flair – Part 1 and Part 2, I showed you how to add base and crown molding to a cabinet. If you are a professional cabinetmaker you probably don’t want to spend your time creating moldings over and over. You need a library of moldings to choose from. You can find thousands of moldings from internet searches, especially the 3D Warehouse. However, many of the interesting moldings are .jpg images such as I used in Country Style Cabinets with a Furniture Flair – Part 2 shown at right. So you may find yourself stuck creating it as I did in Part 2.

However, it only takes a few extra minutes to add your creation to a library of moldings. Hence forth they are available from the Components dialog box (Components library). In this post and accompanying video I will explain how you can create your own library and provide you with a few options for organizing the library. But first I want to review the steps used in Part 2 to create a cross section from a .jpg (or other graphic type) image file. I will use the .jpg profile shown above right found in an internet search. I will call this profile Jeremy.

Steps in Creating a Cross Section From a JPEG Image

If you don’t have a Bezier curve tool already you will need one for this procedure. There are some really good and flexible extensions for SketchUp. I have two favorites:

Fredo6: Bezier Spline v1.9a

SketchUp Team: Bezier Curve Tool v1.1

Bezier Spline is very flexible, draws polylines, Bezier curves and Spline curves. It has numerous icons and can be a little intimidating if you don’t use it a lot, but it is my favorite for drawing complex curves. The Bezier Curve Tool is quick to learn and easy to use and the results are quite astonishing. The Bezier Curve Tool is the one I will use in this post and video.

SketchUp Profile with Discontinuities Labeled

SketchUp Profile with Discontinuities Labeled

Before I get into the steps for creating a cross section I want to make sure we are on the same page with terminology. Curves such as S-curves are made up of curve segments that join at a point of inflection. Points of inflection are points along a curve where the curve changes from convex to concave or concave to convex. They are smooth transitions and mathematically both segments have the same tangent at that point of inflection. Discontinuities on the other hand are points where a curve segment joins another curve segment (or line) and the two segments do not share the same tangent line. At this point of discontinuity there is an abrupt change in direction of the overall curve.

The image at left is the SketchUp model of the cross section (profile) I created by tracing Jeremy above right. I will also refer to this SketchUp model profile as Jeremy in the future. Notice there are five points of discontinuity along the front face. Between these five points are four smooth curve segments. The smooth curve segment are also broken down into sub-segments; at places where there are inflection points or where the sharpness of the curve changes and it is convenient to add a sub-segment.

These sub-segments are called polylines (all curves in SketchUp are polylines ‘smoothly welded’ together). Where these sub-segments join one another, but not at discontinuities, we want to weld them so they do not appear as a line when the profile is extruded. This means you need another tool:

Smustard Team: Weld v3.0.5

With the above terminology and our new tools we are ready for the steps in creating mold cross sections.

  1. Drag and drop a graphical image such as a .jpg file into a new SketchUp model.
  2. Orient the image at the Origin. Since most moldings run horizontally is is usually best to place the image on the Blue/Green or Blue/Red plane. Don’t worry about the size of the image at this point.
  3. Most .jpg images of molding have dimensions shown on them like Jeremy above right. If not you will have to choose a desired dimension for an edge in the image. Measure the actual length of that edge with the Tape Measure tool and record it.
  4. Create a scale factor with the actual dimension and the dimension given on the .jpg or the desired dimension you chose. It’s a simple matter of dividing the two numbers. Chose which is the divisor by whether you need to scale the image up or down.
  5. Use the Scale tool and the scale factor calculated in Step 4 to scale the image to the correct size.
  6. Location of a User's Custom Components Library

    Location of a User’s Custom Components Library

    The image is a component slightly larger than the profile you want to trace and it is also a face that you can trace on. Use the Line and Bezier tools to trace the profile. Here is the very important part: keep your eye on the Inference Engine each time you click on a point and make sure you are actually on the face. The Inference Engine tool tip will say ‘On Face in Image’. If you are not on the face you will be somewhere else in 3D space and in the end will not get a face to extrude.
  7. After the outline is traced and you are sure you have a face to work with locate all the points of discontinuities. Between the points of discontinuity select all the sub-segments with the Ctrl key and the Select tool. Use the Weld tool to join them.
  8. Delete the .jpg image. It is no longer needed.
  9. Make a component of the profile. Give it a name that will make sense to you later when you may want to locate it in the library again.
  10. Save the file in your library file. Here is where I saved my Jeremy.skp file:C:\Users\Joe\AppData\Roaming\SketchUp\SketchUp 2017\SketchUp\Components\Crown Molding

Your Library Appears in the Components DIalog Box List

Your Library Appears in the Components DIalog Box List

If you look in the Window > Preferences dialog box and select the Files page you will see where SketchUp is expecting you to put your library. If you put your library there is will show up in the Components dialog box where you can readily drag it into a model. See the images above right and at left.

Choices, Choices, Choices!

In the video you are about to watch you will see there are several (actually numerous) ways you can build and save your library. The first, as I just explained, is to save only the profiles in the library. Then, when you create a new model and want to trim something you can drag the molding profile into your model. From there you can proceed as I did starting at 50:08 in the Part 2 video or starting at 26:22 in today’s video.

In today’s video you will see that there are two other ways you can store your moldings in your library. You can include the profile and some number of useful components with their bounding boxes corrected, or you can store the profile and some number of useful components without their bounding boxes corrected.

Which of these three methods you use is up to you and how you are comfortable manipulating images or components. Each has its advantages and disadvantages and no one way is right for everyone. You need to develop a method that works for you.

As promised I am going to supply you with two profiles you can use to start your library. Crown Molding ZIP Folder Now it is time to enjoy today’s feature film. Get the popcorn, sit back and relax while I work.