Skip to main content

Brownout Cloud Characterization Using the Modulation Transfer Function

Buy Article:

$30.00 plus tax (Refund Policy)

Abstract:

The paper describes how to extract the modulation transfer function (MTF) of a brownout cloud from video recordings of specific optical patterns. The MTF is a measure of the loss of contrast and resolution caused by the cloud and can be used as the basis for a quantitative metric of brownout severity. The application of two MTF calculation methods to actual flight test data is described. One requires the use of specially designed targets, such as a Siemens star, the other relies on simple dark/light visual edges. The results show that MTF extraction can be successfully performed with a standard consumer-level video equipment and appropriate postprocessing. Also, MTF extraction can be automated using suitable image-processing techniques. The results rigorously quantify the intuitively known facts that the visual degradation caused by brownout is a space- and time-dependent phenomenon and that high spatial frequency features, i.e., fine-grained detail, are obscured before low spatial frequency features, i.e., large objects.

Document Type: Research Article

DOI: http://dx.doi.org/10.4050/JAHS.58.012001

Publication date: January 1, 2013

More about this publication?
  • The Journal of the American Helicopter Society is the world's only scientific journal dedicated to vertical flight technology. It is a peer-reviewed technical journal published quarterly by AHS International and presents innovative papers covering the state-of-the-art in all disciplines of rotorcraft design, research and development. (Please note that AHS members receive significant discounts on articles and subscriptions.)

    Journal subscribers who are AHS members log in here if you are not already logged in.

    Authors can find submission guidelines and related information on the AHS website.

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Partial Open Access Content
Partial Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more