BOG FAQ Quick Jump
About BOG
How much does BOG cost?
Where do I get technical support?
BOG Concepts
What is the difference between Old, Start, and End Angles?
What is tangent ratio scaling?
Running the Program
Do I need GemCAD to run BOG?
Which files does BOG create and use?
How to I get rid of the pop-up Tool Tips?
Running the Program
How much does BOG cost?
BOG is free. Although it represents a substantial investment of time and effort,
at the end of the day, I wrote the program for myself. I have benefitted enormously
from the freely-offered help of others in the faceting community (see here,
for example), and BOG is an opportunity to give something back. You may also
distribute the program non-commercially, although it makes more sense to direct
potential users to http://www.boghome.com
for the most up-to-date software and documentation.
Where do I get technical
support?
I subscribe to all three major faceting lists (there are only three, right?)
and try to read them daily. While you can send questions to me directly at tom@boghome.com,
I would encourage you to use one of these public forums. Not only can the questions
and answers benefit others, but also, there are many gem designers, optimizers,
and cutters out there that are far more experienced than I.
Note that in the spirit of sharing information, I may (anonymously) include
your question in this FAQ. Also please recognize that I will do my best to answer
questions promptly, but I do have a real life (real job, real wife, real kids)
as well.
BOG Concepts
What is the difference between
Old, Start, and End Angles?
BOG uses three types of angles in the optimization
process. The Old angles are the pavillion and crown
angles extracted from the original GemCAD file. By default, BOG assumes these
to be the Start (or initial) angles in the optimization,
although this need not be the case. For example, if the user wants to transpose
a gem design from quartz to CZ, it would make little sense for BOG to start with
the quartz angles. In this instance, the user can override the default Start
angles with more sensible values. The End angles
are the outcome of the optimization process. Typically, the user will run GemCAD
to tangent ratio the Old angles to the End
angles. A description of this process appears here.
What is tangent ratio scaling?
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Gem designers use a process called tangent ratio scaling to change
the shape of a gem for optimal performance. This involves scaling all
the pavillion or crown angles by a certain factor (the tan ratio), which
changes the depth of the stone without altering its plan view - that is
its facet outlines when viewed from above. For example, the gem at right
is shown with three possible crowns. These gems will have different depths
and optical performance, but the same plan view.
Tan ratio scaling is at the heart of BOG, and if you are unfamiliar with
the process, you really should do a little reading. For example, Bob Keller
has an excellent
article on the subject at http://www.rockhounds.com.
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Running the Program
Do I need GemCAD?
You do not need to understand or have GemCAD in order to benefit from BOG,
although it can be useful for applying the results (see here).
GemCAD is an excellent Computer Aided Design program to
generate gemstone designs. You can download a demo at http://www.gemcad.com
I wrote BOG to complement GemCAD and GemRay, the companion program which calculates
the trajectories of light rays through a stone. In simplest terms, I use GemCAD
to design stones and BOG to optimize and cut existing designs.
You will, however, need the GemRay program (version 1.43 or later), which is
available for free download at Robert Strickland's GemCAD site: http://www.gemcad.com
Which files does BOG create and
use?
BOG creates a number of files to store temporary results, images, etc. These
are all located in the subdirectory BOGWork, located in the directory where
you placed the BOG program itself. The program routinely cleans up after itself,
so you shouldn't have a problem with a build-up of files in the BOGWork folder.
Note that this subdirectory also contains the BOG Preferences, a copy of the
GemRay.exe program and a file which restores BOG parameters (thereby allowing
the user to continue where (s)he left off). You should probably avoid placing
other files in the BOGWork subdirectory.
BOG will also create a number of files at the user's request. This includes
sets of Optimization Targets, snapshots of raytraces, and Merit Function Maps
for later study.
How do I get rid of the pop-up
Tool Tips?
ToolTips are small windows that pop up with a hint when you pause the cursor over
a control. Although these can be helpful for beginners, they will sooner or later
drive you crazy. You can disable ToolTips in the Preferences window (About BOG:Customize
BOG). Just un-check the tool tip option.
Back to Main Page.
Documentation maintained by Tom Herbst. Last modified
02-Oct-2002