Next100 - A Dialogue on the Next Century of Energy
Polyhedra - Wolfram Demonstrations Project
visualcomplexity.com | A visual exploration on mapping complex networks
Considering building a small hemisphere for projection, I wondered about the geometry of the sections of a dome. This tutorial, while applying to parachutes, has the formulas for the sections of the hemisphere - a triangle from the pole to the equator has more than 180 degrees total in its angles. I knew that, but not the formulas.
And here's someone who tried to do the same thing for a dome.
Building an inexpensive usable projection dome. - Observatory Central
His numbers for a 10' dome are below.
10 foot diameter with 10 gores. Circumference 31.416 feet = 376.99 inches 1/4 circumference = 94.25 inches which is the length of each gore from spring line to zenith.
From the base (spring line) in inches = B (inches)
Width of gore in inches (1/2 on either side of a perpendicular line running from the center of the base [spring line] to top of gore) = W
B ~ W
0 ~ 37.699
5 ~ 37.568
10 ~ 37.177
15 ~ 36.527
20 ~ 35.624
25 ~ 34.474
30 ~ 33.084
35 ~ 31.465
40 ~ 29.628
45 ~ 27.585
50 ~ 25.35
55 ~ 22.94
60 ~ 20.37
65 ~ 17.659
70 ~ 14.825
72 ~ 13.662
74 ~ 12.483
76 ~ 11.291
78 ~ 10.086
80 ~ 8.87
82 ~ 7.6437
84 ~ 6.4092
86 ~ 5.1676
88 ~ 3.9202
90 ~ 2.668
92 ~ 1.4138
94.25 ~ point
These are the exact widths for the dome described and DO NOT allow any extra material for either overlap (if welding plastic) or a seam (if sewing fabric). You must decide what type of support structure you want. In my small experimental dome I allowed for extra material so that support ribs could be contained.
Also note that the widths of each gore get rather small as you approach the zenith. A central support core usually occupies this space and I would suggest ending the dome material before you reach this point. A circle of white poster board would cover this "hole" in the dome and the entire area where the most sewing would normally be done.
If you go back to the very beginning of this thread you will see a small experimental dome with this type of support. Actually my dear wife has sewn together a much larger one approximately 18 feet in diameter which I plan on using 1/2 inch plastic water pipe for supports. It is actually all put together in four sections of four gores each as I'm not at all sure if an entire dome could be handled at once. My thought was to erect each quarter and then have small velcro patches to hold the four joints together. All of my free time has been used up working on my projectors and I have not attacked the dome. I will need to do this just to see how well it works.
Anyway, I would add an extra two inches to both sides of each gore to allow for sewing at the proper point and then making a loop in which to slide a support strut. I will take some pictures next week to show you what I mean. Right now taxes call (ugh).
--------------------
Ron Walker
Slashdot News Story | A Mathematician's Lament - an Indictment of US Math Education
Are Commercial Buildings Ready for Open-Source Energy Management?
Studies to update and return to train frieight systems.
Aggies rethinking truck freight with electric train | Planetary Gear - CNET News
Some of the illegal settlers in the Sierra del Lacandon Park, Guatemala, have left peacefully. Few details are available so far.
Prensa Libre - Edición electrónica - Portada
Back on the Sketchup track, to update the model.
Three tutorials on bringing CAD drawings into Sketchup, grouped together:
How to use SketchUp with CAD files to create structures | Wonder How To
Main Sketchup video site on YouTube:
YouTube - SketchUpVideo's Channel
And the YouTube site for "Sketchup for Dummies" - excellent.
YouTube - aidanchopra's Channel
An example of an embedded model - let's see how it works.
Lower Eastside Girls Club - Volumetric Model by DaveP - Google 3D Warehouse
Click and then drag side to side.
UPDATE: I had some issues with getting the embed to work and Google folks were quick with help. Here's their first response, which may help other users:
******
First off, there are some models that still don't load properly in the Google Earth Plugin. We're looking at those issues and hope to resolve them soon. Please post links to 3D Warehouse models where there are problems - in the group please! - so we can look at specific examples.
Secondly, the embed functionality has a bit of smarts in it that will intelligently revert embed types depending upon what's available. So if you ask for a Google Earth Plugin embed for a non-geo model, you'll get a 3D View. If you ask for a 3D View for a model where for some reason we don't have the generated images (as in the example posted above), we'll revert to the image type.
Finally, some sites don't allow embedding via the IFRAME technique. Google Sites is an example. In this case, you'll need to create a Google Gadget to do the embed. I slapped something together that I'm happy to share in a thread on the group.
*******
Another version, without as many neighboring buildings:
Put any Google 3D Warehouse model in a webpage. Upload a Sketchup model to the Warehouse and place in a page.
Good tool for 3D blogging in a visualization class. Hmmm...
Official Google SketchUp Blog: Take your 3D with you
An old standby, now for Leopard. It costs, but the free solutions we have tried won't work.
Netopia Timbuktu® Pro For Mac OS - Remote Control Desktop for Mac - Remote Computer Access
For remote screensharing. Other approaches.
BTMM
Mac OS X 10.5: About Back to My Mac security
SSH
macosxhints.com - 10.5: How to use screen sharing remotely and securely