Use of Digital Cameras
NB: This note was written prior to year 2000. Use of
digital cameras has now become very common & its use obvious. It
was not so at the time this note was written. It took a great deal
of effort to educate myself and others around me at the time to realise
Many Architects and Engineers in our observation are not using
Digital Cameras to their full benefit. Even those who happen to be up to date in their use
of IT equipment are failing to grasp the effective use of this amazing tool in building
design and construction.
The main reason for this failing is the users expectations and
comparison of the digital camera with the conventional film cameras. From the technical
have differences. Most users compare the image definition of the two cameras and conclude
that definition of digital cameras is not good enough for their needs.
In our experience, the best use of the digital cameras is to regard them
as a tool to take site notes and then store them on CDs later in the office. When
used in this way, the digital camera becomes an invaluable tool. They allow capturing site
visit views and survey details, which are then downloaded on to the computer with ease,
rapidity and minimal cost. Site personal can also take photographs and then transmit them
to designers, suppliers and clients in any corner of the world by email for immediate
feedback and action.
When writing reports and minutes after site visits, auto display of the
images on the screen in your work background can help confirm or enhance site observations
by a combination of glances and some keen zoom-in studies of these images. In addition,
other members of the team in the office can also grasp the site facts from photos much
easier than hard to repeat wordy descriptions or cryptic site notes.
In short, use digital cameras as a tool to record site facts. Store site
images on CDs. One CD can hold up to about 1000 images at a resolution of 1024x768
low compression. Just one CD may therefore be sufficient for most project needs.
Distribute and recall stored images as and when necessary to enhance the productivity of
your project team with wonderful results.
Inertia Ixy Property of Triangles and Circle Quadrants
In calculations for unsymmetrical bending, the product of inertial
property Ixy is an important sectional property. Yet most engineering books and
section property tables do not include this value for various unsymmetrical sections. In
general, there are 3 shapes for which this property is missing. These shapes are a
Triangle, Circle Quadrant and Rolled Steel Angles.
When performing calculations, it is also necessary to know the sign of
this property. It can be negative or positive depending upon the orientation of the shape.
The following sketches show the formulae and the sign for two of the shapes.
The formulae for the quadrant are:
The formulae for the Triangle are:
For Rolled Steel Angles, the value needs to be calculated for each section
from its dimensions. The sign of this value is however similar to the Circle Quadrants and
Triangles shown above.