Sketchup Sun Position Plugin

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UPDATE:(6/26/11)

There has been a bug fix in the latest version of this plugin which removes an issue with it sometimes breaking other installed plugins. Please upgrade to version 1.2.1 to avoid this problem. A big thanks to both Chris and Fredo for fixing the problem and letting me know about it.

UPDATE:(12/11/09)

The current version of this plugin is now 1.2.0 To check to see if you need to upgrade, simply go to “Draw” on the menu bar and look at the version number on the “Sun Position” menu.

This update is brought to you in large part by archiguy, so big thanks (from me especially) to him.

This version is a great improvement over the earlier ones. The biggest changes to the plugin are the following.

1. The settings are now automatically saved.

2. The Sun’s altitude and azimuth for the day can be saved to a html file for easy viewing.

3. The north angle in Sketchup can be customized. An option for viewing the north angle has also been added.

Introduction

Here is a Sketchup plugin which will draw the path that the sun travels during a 24 hour period. It is fully customizable in that you can choose any location on earth or any date.

The plugin should be pretty accurate. I’ve checked it against other programs, and it looks good; however, you will probably want to double check it yourself if you are doing anything serious.

This plugin is more easily understood with a picture, so I put one below. If you look at the right side, you can see how one of the suns is bigger than the rest. This is where the sun was at the exact moment the plugin was run. This path was drawn in the evening, and, from the picture, you can tell that the sun will be below the horizon within one and a half hours. (The time increment between one sun and the next is half an hour.)

More screenshots available at this link. Screenshots of the Sun’s Path in Sketchup

img10

Also notice that the sun is colored black when it is below the horizon signifying that it is night.

One last thing to look at is how the man which appears when you first start Sketchup is so small that you can hardly see him. If you generate the sun’s path and can’t see it, try zooming out or orbiting around.

Downloading and Installing the Sketchup Sun Position Plugin

Here is the plugin’s download link. sunposition.zip (version 1.2.1)

First, make sure that Sketchup is closed when installing the plugin.

To install (or reinstall) the plugin, simply unzip the folder and place the sunposition.rb file that’s inside it in the following directory.

For a PC it’s  C:\Program Files\Google\Google SketchUp 7\Plugins

For a Mac it’s  /Library/Application Support/Google SketchUp 7/SketchUp/Plugins

If you already had a older version of this plugin installed, you will be asked if you want to overwrite the file. Choose “Yes”.

If you should need the previous version of this plugin for some reason, you can download it by clicking here.

How to Use the Sketchup Sun Position Plugin

In order to run the plugin, first go to “Draw” on the menu bar. Next, go to “Sun Position V??”. Finally, click where it says “Draw Suns.” Once this is done, a window will pop up which will allow you to customize the output.

sun []

Where to Find Your Latitude and Longitude

You can find your latitude and longitude by going here http://www.satsig.net/maps/lat-long-finder.htm. This site gives the Latitude and Longitude in both decimal degree form and degree, minute, and second form. Use the decimal degree form. i.e. 30.187750

If for some reason you can’t find it there, you will have to try elsewhere on the net. I personally found my lat and long on Google Earth by mousing over my house and reading the coordinates.

You could also use a GPS.

Decimal Degrees

If they haven’t been already, the latitude and longitude must be converted into decimal degrees.

For example: N 30 11′ 15.9″ will instead be 30.187750

Here is a website which will do the conversions for you. http://www.uky.edu/KGS/gis/converter.htm

Positive or Negative Lat and Long

Latitude

Make sure you type in the latitude as…

a  Negative number if you’re in the Southern hemisphere

or

a  Positive number if you’re in the Northern hemisphere.

Longitude

Make sure you type in the longitude as…

a Negative number if you’re in the Western hemisphere

or

a Positive number if you’re in the Eastern hemisphere.

Other Inputs

Most of the other inputs in this window are pretty straight forward, so you can probably figure them out by just experimenting with the different settings.

What I will mention though is that it may take awhile to draw the suns if you choose “Yes” for the sphere option. The amount of time is related to how fast your computer is. Sketchup will probably appear as though it has locked up while it creates spherical suns, but just wait a minute and, hopefully, it should go back to normal.

WARNING! Drawing the sun as a sphere may make Sketchup crash, so you should backup your work first.

Another thing is that you should choose to draw the suns as far away from the origin as possible if you are using the plugin for a rough solar analysis. This would be used in conjunction with the “Draw Lines to Origin?” option.

Once the lines are created, you may move where they converge by selecting the “move tool” in Sketchup and then clicking their ending points. Make sure that none of the lines are highlighted while you do this because you only want to move their end points, not the lines in their entirety.

Choosing a Specific Date

If you select, “Choose a Specific Date” for the “Time of year to draw sun?” the window in the picture below will pop up. Simply fill in a date and click OK to calculate the sun’s path for that day.

specificdate

Saving the Output

When generating the path of the sun for a specific date, you may choose to save the output of the sun’s altitude and azimuth for that date as an html file that will open up in your web browser (i.e. Internet Explorer or Firefox).

Keep in mind that choosing to save the output will automatically cause the hour and minute options to default to midnight.

Also keep in mind that the altitude and azimuth will not be generated during the night hours if you selected “No” for “Draw Sun Below Horizon?” in the previous window.

Important! When saving the output, you must make sure that you are using the correct time zone for your area. When it is correct, the biggest sun should show up at the very bottom of the circle. The picture below shows what it should look like. The biggest sun is circled in red.

Note: You may need to choose “Yes” for the “Draw Sun Below Horizon?” option to see the entire circle.

midnight []

Show North Options

First go to “Draw” on the menu bar. Next, go to “Sun Position V??”. Finally, click where it says “Show North.” The window shown below will open.

sun

By default, the solid green line is north. Using the options in this window though, you can change that. For example, if you typed in 90 in the “North Angle” textbox, north would then be in along the solid red line.

The “Display North” textbox simply allows you to see where north is by highlighting it when “True” is selected.

Random Info Regarding the Plugin

This plugin does not take into account precession.

This plugin does not take into account atmospheric refraction.

This plugin calculates the position of the sun using the algorithms from the book Astronomical Algorithms by Jean Meeus. Here is the Amazon link so you can check it out. Astronomical Algorithms

Make sure that both the time and date on your computer are correct. If it’s not, the position of the sun will be incorrect when you choose “Today” for “Time of Year to Draw Sun?”

Technical Support (sort of)

If you have any trouble with the plugin, you can post the problem on the forum. I can’t guarantee that I will be able to help, but I will try.

Also, if you like creating Sketchup plugins, feel free to modify it if you want. Let me know if you make any interesting changes!

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