For a while now I have been looking for a way to visualise things for gaming purposes. For example, if your character is sitting out three thousand feet from a cave and a figure comes out of the cave how "big" does that figure appear to be? Likewise, how big of a target is a robot coming in from a mile out? You can do it in the inverse too. Your character is stranded on an island. They want to make an S.O.S. on the beach out of rocks and branches. How big do you have to make the letters to be seen by a search plane?
To solve this dilemma, since I have great difficulty visualising distances and heights and such, I got together with a friend and we developed a formula to determine how "big" something is at varying distances. To make it useful we did the calculations to determine what font size would be the equivalent of the perspective height for an object. The results are available at http://www.rmtp.ca/images/fontsizes.htm as well as a several examples. Below the examples is a JavaScript that calculates the font for you. Also, I have added an internal frame that takes the calculation and displays an example of how tall the object will appear.
Atramentus Gloaming 
你好，我是位于亚洲的中国人，偶然打开你的空间，用中国话说这应该算是缘份了，能认识你很高兴，期待你的回信。
How are you, I am to locate the Asian Chinese, openning your space by chance, speak in Chinese that this should be regarded as the fate, can know you very happy, look forward to your reply.