Reduction ratios for ISO sheets & scales. A useful list to keep near the photocopier. A3 to A4 = ~70% A2 to A3 = ~70% A2 to A4 = 50% A1 to A2 = ~70% A1 to A3 = 50% A1 to A4 = ~35% A0 to A1 = ~70% A0 to A2 = 50% A0 to A3 = ~35% A0 to A4 = 25% B1 to A1 = ~82% B1 to B2 = ~70% B1 to A2 = ~60% B1 to B3 = 50% B1 to A3 = ~40% B1 to B4 = ~35% B1 to A4 = ~28% … [Read more...] about Reduction Ratios

# Geometry

## Understanding Vectors – Part 2

Written by MickD www.dcservices.net.auIn the last article we discussed basically what a Vector was and had a brief look at the difference between a Point and a Vector. This time we are going to look at what a Vector is made of and try to really get an understanding of why they are so useful as opposed to a Point. Again, not much math just trying to make the concept … [Read more...] about Understanding Vectors – Part 2

## Understanding Vectors

Written by MickD www.dcservices.net.auVectors are very important to understand if you want to use them in your daily manipulations of computer graphics. They are one of the most fundamental building blocks of computational geometry and this will be the first of a few short articles about vectors where I will try to explain them in easy to understand terms. The articles will be … [Read more...] about Understanding Vectors

## Seeing a Rotation Matrix

Written by MickD www.dcservices.net.auOne of the hardest things I found when learning about geometry and computer graphics was how to 'see' a rotation matrix and how they are used, they are a handy thing to have and understand in your programming toolkit for AutoCad also. I won't delve to deep into matrices or calculations, what I hope to achieve in this article is to … [Read more...] about Seeing a Rotation Matrix

## SI International System of Units Measurements

Length - SI Base Unit: metre (m)1 millimetre (mm) = 1000 microns (µm or um)1 centimetre (cm) = 10 millimetres (mm)1 decimetre (dm) = 10 centimetres (cm)1 metre (m) = 1000 millimetres (mm)1 kilometre (km) = 1000 metres (m)Area - SI Base Unit: square metre (m²)1 square centimetre (cm²) = 100 square millimetres (mm²)1 square decimentre (dm²) = 100 square centimetres (cm²)1 square … [Read more...] about SI International System of Units Measurements

## Ratio and Proportion

Ratio is the relationship between two numbers, lines or quantities. Comparing two numbers together forms a ratio, example: 2 is to 4 is expressed as 2:4. Reviewing the 2:4 ratio we notice 4 is double 2 and you could also say 2 is to 4 as 3 is to 6 (3:6). Thus 2:4 and 3:6 are have same ratio. Likewise 3:9 is the same as 4:12.Proportion combines two equal ratios. Thus we say … [Read more...] about Ratio and Proportion