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3D Houses: The most accurate method of house placement?
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Cruiser1



Joined: 27 Sep 2017
Posts: 28
Location: Seattle, WA

Posted: Tue Nov 14, 2017 4:17 am    Post subject: Re: Thanks Reply with quote

astralwanderer wrote:
Mark's point about the 'collapse' of Campanus houses at even quite modest latitudes is also a concern for me. However, the following data shows that the difficulties might not quite be quite as challenging as they first seem. Statistically, Porpyry and Campanus offer the same degree of significance (or greater) than Placidus/Gauquelin divisions of the sphere.
This is interesting research data! Thumbs up I know that Gauquelin Sectors are computed using a technique similar to Placidus cusps, and in fact can be approximated with them (see Astrolog's "-l0" command switch). It looks like similar techniques can be done with other house systems too.

EdF wrote:
As an aside, I consider these representations as "2D" - two astronomical coordinates are represented. Conventional charts are 1D - only the "longitudinal" coordinate is represented.
You're right, at least when considering a single planet. However, I use the name "3D houses" because it's considering the set of planets in a chart as a whole. A standard chart has all planets placed on the 2D plane of the ecliptic, and ignores their 3D latitudes rising up out of that plane. A 3D chart sphere works with the full 3D model of the planets in space with their different latitudes.
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Cruiser1



Joined: 27 Sep 2017
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Posted: Tue Apr 24, 2018 5:19 pm    Post subject: Reply with quote

As a followup to the above, 3D houses are actually similar to Gauquelin sectors in several respects. Gauquelin sectors are computed based on the rising and setting times of planets, which is similar to 3D houses which are also based on the local horizon. When a planet is above the horizon, it's in Gauquelin sectors 1-18, and when a planet is below the horizon it's in sectors 19-36. That's similar to how when a planet is above the horizon, it's always in the 7th through 12th 3D houses, and when a planet is below the horizon it's always in the 1st through 6th 3D houses. Also, when a planet rises, it moves from Gauquelin sector 36 to sector 1, which is similar to how a planet rising moves from the 1st 3D house to the 12th 3D house. When a planet sets, it moves from Gauquelin sector 18 to sector 19, which is similar to how a planet setting moves from the 7th 3D house to the 6th 3D house.

I've composed the following Web page about 3D houses, which summarizes many of the points made on this thread: http://www.astrolog.org/astrolog/ast3d.htm
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Cruiser1



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Posted: Sun Aug 26, 2018 10:01 pm    Post subject: Astrolog 6.40 Reply with quote

A new version of Astrolog has been released, and the new version 6.40 updates "3D houses" and "chart spheres" in several ways. Smile Transit searches now support 3D houses, and will display when planets ingress into different 3D houses (and due to the 3D geometry, these ingress date/times will differ from all ordinary 2D house systems).

Chart spheres are a good way to visualize 3D houses, however they now have the option to show 2D houses. Therefore they're also a good way to visualize the difference between 2D and 3D houses. Below are two chart spheres side by side, which are identical except the left sphere is using 2D houses, and the right 3D houses.

In the left sphere with 2D houses, planetary latitude is ignored when determining house position, which means the 12 house "orange wedges" share the same poles as the 12 sign "orange wedges". Notice how all 12 houses have areas which are above and below the horizon, which is counterintuitive.

In the right sphere with 3D houses, the 12 house "orange wedges" are aligned with the local horizon, and always have their poles at the north and south points on the horizon. In this model, all of houses 1-6 are always below the horizon, and all of houses 7-12 are above the horizon. Because the poles are different, planetary latitude needs to be taken into account to correctly determine house position.


For a comparison not involving chart spheres, below is Astrolog's local horizon display (which is basically a chart sphere so unrolled so it's flat). There are two charts side by side, which are again identical except the left is using 2D houses, and the right 3D houses.

In both of these charts, 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), while the ecliptic and the signs of the zodiac are marked by purple dotted lines (and labeled with purple glyphs). Planets are plotted near the ecliptic, and the Ascendant, 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 2D 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 2D house systems will place it way down in the 6th house.


Also, chart spheres can now display the astronomical constellations on the surface of the sphere. It can display over 1000 fixed stars at once, and stars are displayed according to their brightness. Star configurations are in expected places: For example, below you can see the Big Dipper at the top of Ursa Major (UMa), with its two forward stars forming a line pointing to Polaris the North Star on the meridian. In Orion you can see Orion's Belt of three stars, and in the upper right of Taurus the tight cluster of stars is the Pleiades. The very bright star in Canis Major (CMa) is Sirius, the brightest star in the sky.

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Cruiser1



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Posted: Sun Dec 15, 2019 4:59 am    Post subject: Reply with quote



The animation above (created using Astrolog 6.50) shows how Campanus house cusps change over time. A standard 2D wheel chart is compared side-by-side to a 3D "chart sphere", with both animating the same chart at the same times.

Campanus houses are defined by dividing the local horizon into 12 equal sized wedges (with the horizon as their "equator"). That's similar to how signs of the zodiac divide the celestial sphere into 12 equal sized wedges (with the ecliptic as their equator). Where the ecliptic intersects these houses defines the 12 Campanus cusps. That means Campanus houses are effectively a 3D version of Equal houses, because house sizes are equal from a 3D standpoint. (That's one argument in favor of Campanus being the "best" house system.) A 2D chart wheel is basically a 2D cross-section of the 3D chart sphere, taken on the plane of the ecliptic.

At high latitudes, Campanus can produce narrower houses (at least when looking at the 2D wheel). As can be seen on the 3D chart sphere, this happens at times when the ecliptic is nearly parallel to the horizon, which causes the ecliptic cross section to slice near the point on the horizon where all the houses meet, which means planets can enter and leave certain houses more quickly.

Notice how the Sun and Pluto are tightly conjunct on the wheel chart, however they're actually a bit farther away from each other in space on the celestial sphere, because their ecliptic latitudes differ.
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srsedna



Joined: 22 May 2019
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Posted: Mon Dec 16, 2019 6:06 pm    Post subject: Reply with quote

It would be great if you could study a bunch of cases to find out whether Pluto is "inactive" or at least less powerful in its conjunctions when it's too far away in ecliptic latitude from the other planet/angle.
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Cruiser1



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Posted: Mon Dec 23, 2019 2:14 am    Post subject: Reply with quote

srsedna wrote:
It would be great if you could study a bunch of cases to find out whether Pluto is "inactive" or at least less powerful in its conjunctions when it's too far away in ecliptic latitude from the other planet/angle.
Yes, this would be interesting to investigate! Thumbs up Pluto moves slowly around its orbit, and therefore times when it's near or far from the ecliptic last for quite a few years, similar to the generational influences of Pluto in each sign.

Pluto most recently crossed the ecliptic in 2018, 1930, and 1770. That suggests the decade surrounding today, the decade surrounding the Great Depression, and the decade leading up to the American Revolution were/are especially strong with respect to Pluto energy. Pluto reached maximum ecliptic latitude (+/-17 degrees) in 1839 and 1980, which suggests those decades had minimal influence from Pluto aspects.
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