Re: Google Wall Declination

Thu, 20 Jul 2006 12:49:00 -0700 

Hi John, Roger and all,
I am sorry that I will miss the 2006 meeting - first one I will miss since 2001. Glad to hear you are putting on a DeltaCad workshop. I was unaware about version 6, until you posted your message, John. In checking it out, they are located near the meeting. I would urge someone to contact them and invite them to the NASS conference. Midnight Software, Inc., P.O. Box 77352 ,Seattle, WA 98177-0352 , USA They could do a talk on the scripting that is available in DeltaCad. Ron Anthony was in contact with them ages ago about the scripting language. For your workshop, you might photocopy the article I wrote about 10 years ago for the Compendium. I do think DeltaCad is easy to use --- and I spent hours at my school trying to learn AutoCad -- and never got very far. I printed something from DeltaCad after my first 15 minutes. (I have no $$$$ interest in DeltaCad.) 

Take Care,

Warren Thom



----- Original Message ----- 
From: "John Carmichael"

To: "Roger Bailey"

Hi Roger:

you asked:

I assume that your Delta Cad workshop will cover the transfer of Zon dxf
files to Delta Cad.



Yes, of course!  That will be an important little part of my Delta Cad 
talk: How to import dxf, dwg and jpgs into a DC drawing.



By the way, the new Delta Cad version 6.0 lets you import jpegs now.  The 
older version would only let you import bmps. (which are huge files). 
This makes adding artwork/photos much easier and the files are smaller. 
You should upgrade to 6.0 if you haven't already done it.  It has other 
useful features that 5.0 did not have.



You might try importing a standard jpeg photo of your building wall in DC. 
Then copy and paste a the DC drawing of your sundial on top of it. You 
will see the DC sundial drawing on top of the photo.




----- Original Message ----- 
From: "Roger Bailey" <[EMAIL PROTECTED]>

To: "John Carmichael" <[EMAIL PROTECTED]>
Sent: Thursday, July 20, 2006 9:17 AM
Subject: RE: Google Wall Declination



Hi John,

I assume that your Delta Cad workshop will cover the transfer of Zon dxf

files to Delta Cad. The ability in Delta Cad to "select all" and "copy" 
to

get the lines only as an overlay was a new one on me. Every other way I

tried gave me an opaque white background, useless as an overlay. This 
works

for PowerPoint, not for Photoshop or Word. There you get the white
background.

See you soon,

Roger

-----Original Message-----
From: John Carmichael [mailto:[EMAIL PROTECTED]
Sent: July 20, 2006 7:07 AM
To: Roger Bailey
Subject: Re: Google Wall Declination


Very Cool Roger!


----- Original Message -----
From: "Roger Bailey" <[EMAIL PROTECTED]>
To: "Sundial Mail List" <[email protected]>
Sent: Wednesday, July 19, 2006 11:29 AM
Subject: Google Wall Declination



We have had many discussions on this list on how to determine the
declination of a vertical wall. Let me suggest a new technique for not
only
wall declination but also location (latitude and longitude). Use the
satellite images on "Google Earth". An example is posted in three
PowerPoint
slides at:
http://www3.telus.net/public/rtbailey/WalkingShadow/WallDecG.ppt


For my "Timelines" presentation, I was interested in analysing sundials 
on
mosques in Istanbul. When I took pictures of the three sundials on the 
New

Mosque "Yeni Camii", I did not take field measurements to determine the
wall
declination. No problem. Start up Google Earth and fly to Istanbul.
Without

rotating, just using the X/Y controls, zero in on the New Mosque and 
save
the image. You can insert the saved image into a PowerPoint 
presentation,

add the North South vertical axis, draw a line along the wall and
determine
the wall declination, perpendicular to the wall.

Then start up Zon 2000 and enter the latitude and wall declination from
the

Google image into Fer de Vries program. Calculate for the example 
sundial:
local hours, Italian hours and Islamic Prayer times. Clip the Zon 
drawing,
save it as a dxf file and load the dxf file into Delta Cad. There you 
can

trim the lines to recreate the dial on the wall. Select all and copy the

lines as an overlay on the photograph (corrected for perspective) in 
your

presentation.

The Google Earth technique is sufficiently accurate with large buildings
and
high resolution images. I have used it successfully for three mosques in
Istanbul and the Klementinum in Prague. It even works for my home! The
full
story will be shown in Vancouver.


A conclusion from this analysis is the sundials on the mosques in 
Istanbul

show the mid afternoon prayer time "Asr" as in the standard horizontal

shadow length definition. But a different convention was used in 
Istanbul

for "Zuhr", the prayer just after noon. The Zuhr lines are not based on
the
altitude giving the horizontal shadow length as the noon shadow length +
25%
of the vertical gnomon height.

Regards,

Roger Bailey
Walking Shadow Designs
N 48:38:22.90, W 123:24:10.80, declining east 90 degrees by Google Earth


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