WEBSITE AND WEBSITE GRAPHICS CREATED WITH XARA DESIGNER 6 PRO Positioning and Other Issues In this section I want to mention some issues I had trying to make things work properly. Sizing One of the annoying things that Xara 3D does is resize imported shapes to make them all conform to the same height. This often has the effect that shapes that had specific size and position relationships to each other before importing, lose that relationship when they appear in Xara 3D. You can correct that within Xara 3D, but the tools to do so can be a bit clumsy, and I don’t normally use them. Some years ago, someone (no-one really remembers who, now, but it wasn’t me!) realized that you can preserve such size and position relationships by creating a pair of pixel-sized dots at the top-left and bottom right of the working area in Xara Xtreme for example, and that by adding the two dots to each shape before exporting it to Xara 3D, all such shapes acquire the same overall bounding-box, that of the two dots. Thus Xara 3D makes no attempt to resize them, as they already have the same size. In the context of the arc segments for the Hollow Earth, the problem is that depending on which arcs are preserved in a given ring the overall height may differ from ring to ring, so Xara 3D will adjust their relative sizes. To prevent this, the sizing pixels are brought into play. You can see them in this screen shot from Xara 3D, I’ve exaggerated the bevel and reduced the extrusion to make them easier to see. This is an earlier version, with 72 rings, and also shows the individual arcs. 2010 Mike Sims The use of sizing pixels also solves a related issue, to do with horizontal positioning. The Hollow Earth depends on all the rings having a common centre. If the arc segments of a given ring had an arc crossing the equator at one side of the earth, but had no arc segment on the opposite side at the equator, the centre of the arc group’s bounding box would not correspond to the centre of the ring the arcs are supposed to lie on. But using sizing pixels makes the arcs or even the rings’ centres irrelevant, as it is the centre of the sizing pixels’ bounding-box that determines the positions of the arcs within them, and all the segments have the same set of sizing pixels, and therefore a common centre, both horizontally and vertically.  For reasons of symmetry, due to the need to have the first and last rings adjacent to each other with one being rotated almost 180° compared to the other, the ring centres must be closely matched to the sizing pixels centre. The presence of the sizing dots doesn’t really intrude in the image because they are far enough away from the main shapes that they can easily be cropped out of any final image. How Many Rings? The number of rings used in the model makes a significant difference to the appearance of the continents on the globe, since the width of the rings effectively sets the horizontal resolution of the visible detail. My first version had 60 rings because 60 is an easy number to work with when considering angles, and at that time I was primarily trying to prove the concept. Each ring appears on the equator twice, with a band at the front and a band at the back, making 120 bands around the equator, so the smallest horizontal detail would be 1/120th  of the circumference at the equator, that is, 3° across, or equivalent to about 209 miles. That version looked extremely crude, quite apart from the inadvertent distortion of the continents mentioned earlier. The coastlines looked very blocky. I clearly needed more rings. H    1    2    3    4    5    6    Download Zipped Tutorial