3D Houses: The most accurate method of house placement?

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The concept of three dimensional houses or "3D houses" refers to a method of placing planets in one of the 12 houses that requires considering the planet's latitude in addition to its zodiac longitude. All the various classic systems of house division (e.g. Placidus) attempt to define a single zodiac position for each house cusp. That model is simple and easy to work with, however it's limited because it doesn't take into account the third dimension, or a planet's ecliptic latitude. "3D houses" is not a standard system of house division like others, because it goes beyond the old model of picking a single zodiac position for each house cusp.

Visualize the nature of a house to begin with. The sky or celestial sphere is divided into 12 equally sized wedges (like pieces of an orange) with respect to the local horizon, with houses 1-6 below the horizon, and houses 7-12 above it. Similarly, houses 10-3 are to the east of the meridian, and houses 4-9 are to the west of the meridian. To compute 3D houses or determine which house a planet lies within, convert the planet's zodiac longitude and latitude to local horizon coordinates centered on the prime vertical. That means the azimuth or 0-360 degrees (representing house positions 1-12) follows the prime vertical from the horizon east point through the west point via the nadir. Similarly, the altitude or -90 to +90 degrees ranges from the north to south points on the local horizon.

The signs of the zodiac are also a set of 12 "orange wedges", however they're oriented to a different coordinate system, or more specifically are rotated to be aligned with the ecliptic. The fact that houses consider the local horizon, and zodiac positions consider the ecliptic, and standard house systems attempt to use ecliptic coordinates to fully define houses, could be considered a distorted model and therefore less accurate astrology. Perhaps the reason why there's so much debate about which house system is correct, is that they're all wrong! In other words, each house system only seems to work in certain circumstances when the planetary latitudes happen to place them in the correct house. It's like how a slow or stopped clock is still correct a couple of times a day! ;)
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For a visual example, see the image above for a local horizon display of my chart in "Astrolog". The middle horizontal line is the horizon, the middle vertical line is the south meridian, the vertical lines on either side of it are the prime vertical passing through the east and west points, and the far edges are the north meridian. The 12 houses are marked by the green dotted lines (and labeled with green numbers). The ecliptic and the signs of the zodiac are marked by dark blue dotted lines (and labeled with blue glyphs). Planets are plotted near the ecliptic, and the Asc, MC, and house cusps are plotted where they intersect the ecliptic. Notice how the star Sirius (labeled "Sir") is clearly in the 5th house below the horizon, however with a zodiac position slightly later than the Descendant, all ordinary house systems will place it in the 7th house, making one think it's above the horizon! Similarly, the star Polaris (labeled "Pol") is high in the sky on the meridian and therefore correctly on the 10th cusp, however ordinary house systems will place it way down in the 6th house.

With 3D houses, a standard chart wheel display doesn't work well. That's because house cusps don't have single zodiac longitude positions anymore. In effect there needs to be something equivalent to a "chart sphere" instead of a "chart wheel". With 3D houses, each planet is still unambiguously in a single house. That means it's still possible to have a simple table listing each planet's zodiac position and house placement. However, it's important to realize that two planets at the same zodiac position may be in different houses, because their latitudes differ.

Note that Campanus is the standard house system most similar to 3D houses. Campanus houses are defined by the intersection of the ecliptic with the 12 house "orange wedges". That means Campanus houses and 3D houses give the same house placements for planets exactly on the ecliptic. Since most planets are near the ecliptic, and it's only things like asteroids and especially fixed stars that are located any significant distance from it, Campanus houses can be used as a rough approximation for 3D houses.

In one of the articles on this site by Deborah Houlding, she also considers 3D houses and "chart spheres", or how a planet's latitude can change what house it's properly within. Below are two excerpts from: http://www.skyscript.co.uk/houprob_print.html#6back
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"Those who consider the three dimensional perspective important, argue that defining house positions by zodiacal degree alone can often prove inaccurate since it assumes that the cusps cut through the ecliptic in a straight line whereas in reality the lines are curved, formed by great circles passing through the earth and meeting at the poles. This curvature results in an angle that moves several degrees across the ecliptic when latitude is considered. David McCann has illustrated how this distortion manifests in the chart of William Butler Yeats, for whom Pluto has a latitude of 15S. By zodiacal degree alone Pluto appears to be in the middle of the 2nd house but when latitude is taken into account it is actually on the 3rd house cusp."

"Rudhyar also proposed that a future development of the houses could utilize Campanus as the basis of a three dimensional 'birth sphere', in which the effect of planetary latitude could be fully acknowledged; although to do so requires some alternative way of representing this information other than our two-dimensional chart forms which only show measurements along the ecliptic."

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This is an intriguing idea. There is this age-old problem of mapping a 3D form onto a 2D sheet of paper. Or computer screen, which now has many more graphic possibilities.

Can you say how reading a chart with a 3D house system would change your insights, compared to a conventional system?

I think declinations (parallels, counter-parallels) do have meaning in chart interpretation.

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Hi Walter, and welcome to Skyscript!

I was immediately thinking of what Rudhyar wrote when I saw this topic. Great how you took this idea up and developed it into something applicable. :)

So I take it that the latest version of Astrolog can do this kind of calculation? I have known this program for many years and appreciate the fact that it includes numerous techniques that many a commercial astro software is incapable of.

Keep up the good work!

Michael
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waybread wrote:Can you say how reading a chart with a 3D house system would change your insights, compared to a conventional system?
The short version is they wouldn't change. :) "3D houses" is merely a more accurate version of house placement when compared to a standard "house system". The insights gained from a planet being in a house are the same. That said, 3D houses does lead to additional types of analysis that can be done...
waybread wrote:I think declinations (parallels, counter-parallels) do have meaning in chart interpretation.
Indeed, (contra)parallel aspects are one existing technique that takes into consideration the latitude of planets. However, they only look at latitude separately from zodiac position longitude. One additional type of analysis that can be done is "3D aspects", or looking at the true 3D angle/orb between planets, taking into account both longitude/latitude at the same time on a great circle across the celestial sphere. "3D aspects" suggests that an exact time New Moon in which the Sun and Moon are different by 3 degrees in latitude, has the same orb or energy as a standard Sun/Moon conjunction different in longitude by 3 degrees.
Astrolog 7.60 freeware downloads: http://www.astrolog.org/astrolog.htm :)

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Michael Sternbach wrote:Hi Walter, and welcome to Skyscript! So I take it that the latest version of Astrolog can do this kind of calculation?
Thank you for the welcome, and it's good to be on this quality forum. :) Yes, the latest version of Astrolog (6.30, just released the other week) can do the new calculation types described. :'
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  • 3D Houses: You can toggle whether house placements are determined using "3D houses". Select the "Setting / House Settings / 3D Houses" command, or just press the "a" key.
  • Chart Spheres: Show them with the "Graphics / Show Chart Sphere" command. An example chart sphere, or 3D wheel chart, is above. Sign wedges are in blue, and house wedges are in green. Aspect lines (not shown in this picture) are interesting because they're 3D lines passing through the middle of the sphere. For more explanation about this display see: http://www.astrolog.org/ftp/updat630.htm
  • 3D Aspects: Turn on 3D aspects in the "Setting / Calculation Settings" dialog. If you do this, aspect grids will change in that orbs will increase by up to the latitude difference, causing some aspects to disappear if they're pushed beyond the orb limit.
  • Transit graphs: Astrolog 6.30 also introduces transit graphs, which map the orb of aspects over time, such as seen below. Yes, turning on "3D aspects" will affect it, and cause most of the peaks to be rounded down somewhat, because most aspects no longer ever become exact since their latitudes differ.
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Astrolog 7.60 freeware downloads: http://www.astrolog.org/astrolog.htm :)

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The chart in your 4th post would take some getting used to, and possibly there is a little more legibility to get to with the graphic design compared to the Astrodienst fixed stars chart, but I really liked how it showed the 3-D solar system at a glance. It would be nice if the ecliptic were more visible, for example. In your example, it seemed to highlight Saturn as an outlier, so this type of chart might draw more attention to particular placements in the 2D chart. Then showing the declinations is to me a big advantage, though I would have to look at degrees, as well as just the planetary symbols.

Are you in touch with Alois Treindl at Astrodienst www.astro.com? They have a huge chart selection but not one that captures the 3D solar system like this one. It would be nice if they did.

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Hi Walter,

I just downloaded the new version. The additional functions rock! :lala

I wrote a brief but enthusiastic review of your program for the astrology section of this new Tarot forum that I helped founding:

http://eclectic.jomay.com/viewtopic.php ... 9013#p9013

If you wish to subscribe and talk about it on Eclectic Tarot yourself - be my guest! :)
Last edited by Michael Sternbach on Fri Nov 03, 2017 11:39 pm, edited 1 time in total.
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waybread wrote:The chart in your 4th post would take some getting used to, and possibly there is a little more legibility to get to with the graphic design compared to the Astrodienst fixed stars chart, but I really liked how it showed the 3-D solar system at a glance. It would be nice if the ecliptic were more visible, for example. Are you in touch with Alois Treindl at Astrodienst www.astro.com? They have a huge chart selection but not one that captures the 3D solar system like this one.
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Indeed, chart spheres are new and take some getting used to. The sphere is by default displayed transparent, such that both sides of the sphere are overlapping. Being 3D, chart spheres are effective when animated, to get a better sense of their depth. See above for an animated chart sphere!

There are quite a few ways chart spheres can be customized in Astrolog, such as you can select what things to display and what colors to use for them. The ecliptic was in dark blue in the first picture, but in this animation I've changed it to a brighter purple. You can also see aspect lines crossing through the interior of the sphere.

Yes, I've been in contact with Alois Treindl at Astrodienst for a number of years. :' Astrolog computes its planetary positions using the Swiss Ephemeris that Astrodienst created. Astro.com features "Pullen charts" which call Astrolog and display the result in your browser, although currently it uses an old version of the program. I've posted about the newest version on the Swiss Ephemeris forums.
Astrolog 7.60 freeware downloads: http://www.astrolog.org/astrolog.htm :)

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Michael Sternbach wrote:I just downloaded the new version. The additional functions rock! :lala I wrote a brief but enthusiastic review of your program for the astrology section of this new Tarot forum
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I'm glad you like the new Astrolog version 6.30. Thank you for writing and sharing your positive review of it! :' I'll indeed subscribe to that forum, and not just to talk about Astrolog. Outside of astrology, I've actually produced my own deck, titled "The Labyrinth Oracle: Cards for the Spiritual Path". This deck is also hosted on my astrolog.org site at: http://www.astrolog.org/oracle.htm

Although "The Labyrinth Oracle" is primarily Maze and Labyrinth themed, it does have some relation to astrology. There are 109 cards total, although minus the final "joker" card there are 108 cards, divided into 12 groups of 9. That makes one group for each sign of the zodiac, in which each group of 9 is a decanate of decanates, or a triplicity of triplicities.
Astrolog 7.60 freeware downloads: http://www.astrolog.org/astrolog.htm :)