CADENCE AEC Tech News #102 (July 24, 2003)

23 Jul, 2003 By: Lachmi Khemlani

In This Issue: SketchUp 3.0

  • Dimensions and Annotations
  • Modeling Enhancements
  • Improved Rendering and Export Options
  • Limitations and Conclusions
  • Relevant Links

In Issue #80 of the AEC Tech newsletter (, I provided an overview of SketchUp, an application for 3D design exploration, which is targeted towards the conceptual phase of design and has specifically been developed to be easy, intuitive, and fun to use. In this issue, we will look at the enhancements in the latest release of the program, Version 3.0, released in June and recently on show at the MacWorld Expo in New York. Recall that SketchUp, initially a Windows-based application, was also made available for the Mac platform last year, so it can now cater to creative design professionals on both platforms.

The key focus of the new release is to extend the repertoire of the program beyond conceptual design to detailing and documentation by introducing dimensioning and annotation capabilities. In addition, there are several improvements along the modeling, rendering, and export fronts.

Dimensions and Annotations

The last time I reviewed SketchUp in Issue #80, I wrote that it had no dimensioning or annotation capabilities. A major enhancement in Version 3.0 is the addition of these capabilities. There is a single Dimension tool, which automatically creates the appropriate dimensions based on the selected entity--linear dimensions for an edge or two points, and radius or diameter dimensions for an arc or circle. Dimensions can be added in 2D or 3D views. Regardless of the view in which the dimension is added, it appears in all views. The same is true of text, which is created by a single Text tool. The text can be placed independently or by associating it with a selected element, in which case a leader line is automatically added, connecting the element to the text. A useful, smart feature is the automatic left or right justification of a multi-line block of text, depending upon which side of the element the text is positioned.

As with all the other tools, the options associated with the Dimensions and Text tools are listed in a common Preferences dialog rather than in individual dialog boxes. These options include text size and font, whether the dimension text should be horizontal or aligned with the dimension line, type of arrow head for dimension lines and leaders, the ability to hide small or foreshortened dimensions, and so on.

While the new dimensioning and annotation capabilities are certainly useful and necessary additions, I did find a few problems with them. Because these entities are view-independent and appear in all views, the result is quite confusing (for instance, a vertical dimension or annotation added in an elevation view also appears in a plan view). The option to hide foreshortened dimensions that is available in the Preferences dialog does help to take care of this problem to a certain extent, but text is displayed in all views. Of course, you could choose to create dimensions and annotations for different views on different layers, and turn off the layers you don't need for a particular view. Nevertheless, it would help if dimensions and annotations were smart enough to automatically get turned off for views they weren't relevant to. I also found that after adding dimensions and text, planar views automatically acquire a perspective effect to display the dimensions and annotations created on different planes, and, thereafter, you cannot get back to a regular orthogonal planar view.

Modeling Enhancements

A big improvement on the modeling front in SketchUp 3.0 is that entities such as arcs, circles, polygons, and polyline curves (the entities created with the Freehand tool) no longer get broken up into individual line segments after creation. Connectivity is now maintained, so the whole entity gets selected when you click on an edge. This makes selection of these entities faster, and also makes editing operations such as moving, resizing, and so on much easier. Rectangles and polylines, however, continue to be comprised of separate segments, as before, but any problems with selection have now been mitigated because of a new selection capability, described below.

I am pleased to note that one of the major limitations of SketchUp that I wrote about in the last newsletter has been fixed in this release. Recall that previously, you could directly select only a single edge or face of a 3D object; the entire object couldn't be selected except by using a marquee to enclose all its faces, which isn't easy when the object is complex and overlaps with other objects. Now, this problem is eliminated by a new multi-click system: a single click selects only the edge or face; a double-click selects all the connected edges of a face; a triple-click selects the entire object. Options in a contextual menu also allow you to expand the selection to other objects on the same layer, or with the same material. The new selection system works the same way with 2D objects; thus, a multi-segment polyline can be fully selected by triple-clicking on it.

Other modeling enhancements include new Equidistant and Tangent inferences that allow chamfers and fillets to be modeled more accurately and efficiently; and the ability to dock the Layer Manager for performing layer related operations more easily.

Improved Rendering and Export Options

A useful new feature in SketchUp 3.0 is the ability to soften the edge of an object, which makes the edge automatically hide itself when it isn't displayed in profile. A softened edge can additionally be smoothed, which renders its adjoining faces with a smooth tonal gradient. These abilities can be used to give a more rounded appearance to a facetted model, useful when modeling curved forms. Curved entities such as arcs, circles, and polyline curves automatically produce softened and smoothened edges when they are extruded with the Push/Pull tool. Thus the faces extruded from these curves will properly display profile edges and hide internal edges, as the viewpoint changes, and be rendered with a smooth tonal gradient.

Prior to Version 3.0, SketchUp offered transparency only through an X-ray tool that displayed globally, in a shaded mode, all the faces of the objects in the model, including the hidden ones. The new release allows you to create transparent materials, allowing individual faces or entire layers to have variable transparency attributes. This comes in handy not only for modeling real-life transparent materials such as glass, but also for creating abstract conceptual diagrams. While this new capability does have its limitations--the display is not fully accurate and transparent shadows cannot be obtained--it is sufficient for the conceptual design stage, the focus of the application.

SketchUp has expanded its repertoire of export options with Version 3.0, allowing better communication with other programs and improved workflow. Animations can be exported in AVI (Windows only), MOV, and QuickTime (Mac only) formats. Models can be exported as filled polygons to vector file formats such as EPS and PDF. The new VRML output capabilities for interactive Web viewing support material texture and transparency.

Limitations and Conclusions

SketchUp continues to have a few of the limitations I pointed out in my last review in Issue #80. The first point of any modeling entity such as a line, arc, or rectangle still cannot be specified numerically with respect to the coordinate system; it can only be selected graphically in the modeling window. The Push/Pull tool still doesn't work in wireframe mode and continues to give the wrong result when an outline is pushed beyond the depth of the object for subtraction. I also found the new release somewhat buggy in its dimensioning and annotation features and susceptible to crashing, indicating some issues with stability.

However, with a total price tag of $495, and an upgrade cost of $95, SketchUp continues to remain a convenient and affordable modeling alternative for 3D conceptual design that is easy to learn and fun to use.

Relevant Links


MacWorld Expo 2003 in New York: