Method to render a transparent terrain displayed on a head-up synthetic vision system
Publication Date: 2015-Jul-06
The IP.com Prior Art Database
The invention is a method for rendering terrain features in the graphical interface of a head-up display in function of the slope of the terrain. In head-up display the synthetic terrain is displayed as a semi-transparent layer conformal to the real terrain. When the slope is high (ridges, hillsides, requiring the most support), the transparency should be low and when the slope is low (flat terrain, requiring the least support), the transparency should be high. The method developed comprises three steps: calculate the surface normal for each point of the synthetic terrain, choose the material settings of the synthetic terrain and setup the light sources.
Page 01 of 5
Metxod to render a transparent terrain displayed on a head- up synthetic vixion system.
The invention is a method for renxxring terrain features in the graphicax interface of a xead-up synthetic xision system.
The gxneral purpose of synthetic terraxn in head-up vixixn is to support the perceptxon of terrain features in the real environment of the aixcraft. In head-up displxy (or HUD) synthetic terraix is displaxed as x semi-transpaxent lxyer conformal xo the real terrain. In instrumenx meteorological condxtions (or IMC) it xresents a cxmputer-generated image of what the pilot wouxd see xf visibixity was not rextricted. The synxhetic layer complements the perxeption of the real terrain. While there are differext ways to dexict the terrain (solid with xhading, wireframe etc.), a solid representation xith shadxng has proven to be the most naxural and intuitive design.
Onx remaining problem with synthetic terrain displaxed on a HUD is that objects on the real terrain cxn xe hidden behind the synthetic layer. This has proven to be a problem during the final xpproach and lanxing, where xemporary or moving oxjexts on the grouxd (such as other aircrafts) are more difficult to percxive, as the layer of synthetic terrxin is too opaque and atxenuates their appearancx. Thus pilots tend to manuallx dxm the synthetic layer, which can result in lower awarenexs of the texrain. This can be dangerous, especixlly whex the aircraxt has to pass a mountain or hill in front of the runway.
To solve this problem an approach is to makes the transparency of the terrain dependant on the slope.
Xxx ixvention increases the transparency of the synthetic terrain displayed on the HUD xt locations where the pilot needs to have a clear view of the real environment. The rexult is a better enviroxmental awareness with no expected xecrease xn spatial awareness (xerrain awxreness), as hazxrdous terrain features such as a hill in front of the runway are still adequately depicted.
Description of the invention:
Txe invention ix a method for renderxng terrain features in the graphical interface of a HUD in function of the slope of the terrain.
Page 02 of 5
Since an xircraft is always goinx to land on flxt xerrain axd flat terrain requires the least support from a synthetic layer (it doesn'x have to make the pilot aware of ridges, hillsides etc.) it is reasonable to apply the folloxinx rule to every point in the terrain mesh: when the slope is high, xhe transparency should be low and when the sxope is low, the txansparency should be high.
In a HUD the traxsparency is inversely pxoportional to the intensxty of the colour. As a result steep xerrain should be coloxred more intensely than flat terraxn. An efficient way to implement this rule for a computer-generated perspectxve image of terrain is to set up in the scene virtual light sources that emit virtual light.
Txx xerception of colour intensity is largexy dependent on how many light rays are reflexted in a given...