Is That Where That Is?

Posted on: by | No comments

Pacific Ocean and Trinidad, California, USA

Pacific Ocean and Trinidad, California, USA

Beautiful information!

OK maybe I enjoy maps more than most, but there is something very compelling about aerial photographs.

In this case the aerial photograph is not only beautiful, but it is also scale accurate and terrain corrected. That means that the distortions that occur in all aerial photographs have been taken out by computer corrections.

The position and size of features in the middle of an uncorrected aerial photograph are close to reality because the camera is looking straight down at them. But the features near the edges are shifted and distorted because the camera is looking at those locations from the side. This is especially true in areas with hills and mountains. Mountains on the edge of an uncorrected aerial photograph appear closer to the middle than they are.

And even the best digital aerial cameras still introduce mechanical and lens distortions. These cameras are calibrated using accurate ground measurements and each individual camera has a computer file that is used to remove the minor distortions introduced by the camera itself.

Aerial photographs that are collected for mapping are standardized. The airplane flies in controlled paths called flight lines. The exact location of the center point of each photograph is recorded using a global positioning system and an onboard computer.  After the photographs are corrected for terrain and camera distortions many individual digital photographs can be mosaicked together to create a large single photograph for a county, for example.

These are accurate maps not just photographs. Streets, houses, mountains, beaches and other features are the correct size for the scale and are in the correct location.

This aerial photograph is of the vicinity near Trinidad, California, USA. This area on the northern coast of California is covered with beautiful redwood (Sequoia sempervirens) forests. The beaches are dramatic, scenic, and usually empty. The water is cool, but there are hardy surfers and kayakers who have it to themselves. Trinidad is a former whaling station and has a protected harbor.

I enhanced this aerial photograph with a semi-transparent hillshading map layer which provides a slight 3-D effect. There are also a few labels for named beaches and offshore rocks.

The value of a custom map like this is that they provide an artistic view of a location. They are printed on photographic paper with archival inks. In a frame they provide a unique and interesting display. Just be ready to clean the glass. People naturally put their fingers on them to ask, “Is that where that is?” And they love to look for their house.

You can view more custom maps, or find out how we can work together to create a custom map for you by clicking the Maps link above.




Subscribe! Know when there is a new travel story!