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[[File:Show how 3D real time ambient occlusion works 2013-11-23 10-45.jpeg|thumbnail|The ambient occlusion map for this scene darkens only the innermost angles of corners.]]
It is very common to have a dental emergency -- a fractured tooth, an abscess, or severe pain when chewing. Over-the-counter pain medication is just masking the problem. Seeing an emergency dentist is critical to getting the source of the problem diagnosed and corrected as soon as possible.<br><br>Here are some common dental emergencies:<br>Toothache: The most common dental emergency. This generally means a badly decayed tooth. As the pain affects the tooth's nerve, treatment involves gently removing any debris lodged in the cavity being careful not to poke deep as this will cause severe pain if the nerve is touched. Next rinse vigorously with warm water. Then soak a small piece of cotton in oil of cloves and insert it in the cavity. This will give temporary relief until a dentist can be reached.<br><br>At times the pain may have a more obscure location such as decay under an old filling. As this can be only corrected by a dentist there are two things you can do to help the pain. Administer a pain pill (aspirin or some other analgesic) internally or dissolve a tablet in a half glass (4 oz) of warm water holding it in the mouth for several minutes before spitting it out. DO NOT PLACE A WHOLE TABLET OR ANY PART OF IT IN THE TOOTH OR AGAINST THE SOFT GUM TISSUE AS IT WILL RESULT IN A NASTY BURN.<br><br>Swollen Jaw: This may be caused by several conditions the most probable being an abscessed tooth. In any case the treatment should be to reduce pain and swelling. An ice pack held on the outside of the jaw, (ten minutes on and ten minutes off) will take care of both. If this does not control the pain, an analgesic tablet can be given every four hours.<br><br>Other Oral Injuries: Broken teeth, cut lips, bitten tongue or lips if severe means a trip to a dentist as soon as possible. In the mean time rinse the mouth with warm water and place cold compression the face opposite the injury. If there is a lot of bleeding, apply direct pressure to the bleeding area. If bleeding does not stop get patient to the emergency room of a hospital as stitches may be necessary.<br><br>Prolonged Bleeding Following Extraction: Place a gauze pad or better still a moistened tea bag over the socket and have the patient bite down gently on it for 30 to 45 minutes. The tannic acid in the tea seeps into the tissues and often helps stop the bleeding. If bleeding continues after two hours, call the dentist or take patient to the emergency room of the nearest hospital.<br><br>Broken Jaw: If you suspect the patient's jaw is broken, bring the upper and lower teeth together. Put a necktie, handkerchief or towel under the chin, tying it over the head to immobilize the jaw until you can get the patient to a dentist or the emergency room of a hospital.<br><br>Painful Erupting Tooth: In young children teething pain can come from a loose baby tooth or from an erupting permanent tooth. Some relief can be given by crushing a little ice and wrapping it in gauze or a clean piece of cloth and putting it directly on the tooth or gum tissue where it hurts. The numbing effect of the cold, along with an appropriate dose of aspirin, usually provides temporary relief.<br><br>In young adults, an erupting 3rd molar (Wisdom tooth), especially if it is impacted, can cause the jaw to swell and be quite painful. Often the gum around the tooth will show signs of infection. Temporary relief can be had by giving aspirin or some other painkiller and by dissolving an aspirin in half a glass of warm water and holding this solution in the mouth over the sore gum. AGAIN DO NOT PLACE A TABLET DIRECTLY OVER THE GUM OR CHEEK OR USE THE ASPIRIN SOLUTION ANY STRONGER THAN RECOMMENDED TO PREVENT BURNING THE TISSUE. The swelling of the jaw can be reduced by using an ice pack on the outside of the face at intervals of ten minutes on and ten minutes off.<br><br>If you have any issues concerning the place and how to use [http://www.youtube.com/watch?v=90z1mmiwNS8 Dentists in DC], you can speak to us at our own web site.
 
In computer graphics, '''ambient occlusion''' is used to represent how exposed each point in a scene is to [[Shading#Ambient_lighting|ambient lighting]]. So the enclosed inside of a tube is typically more occluded (and hence darker) than the exposed outer surfaces; and deeper inside the tube, the more occluded (and darker) it becomes. The result is diffuse, non-directional lighting throughout the scene, casting no clear shadows, but with enclosed and sheltered areas darkened. In this way, it attempts to approximate the way light radiates in real life, especially off what are normally considered non-reflective surfaces.
 
Unlike local methods like [[Phong shading]], ambient occlusion is a global method, meaning the illumination at each point is a function of other geometry in the scene. However, it is a very crude approximation to full [[global illumination]]. The soft appearance achieved by ambient occlusion alone is similar to the way an object appears on an overcast day.
 
==Implementation==
In real-time games, [[Screen space ambient occlusion]] can be used as a faster approximation of true ambient occlusion, using pixel depth rather than scene geometry to form an ambient occlusion map. However, newer technologies are making true ambient occlusion feasible even in real-time.
 
Ambient occlusion is related to accessibility shading, which determines appearance based on how easy it is for a surface to be touched by various elements (e.g., dirt, light, etc.).  It has been popularized in production animation due to its relative simplicity and efficiency. In the industry, ambient occlusion is often referred to as "sky light".{{Citation needed|date=June 2008}}
 
The ambient occlusion shading model has the nice property of offering a better perception of the 3d shape of the displayed objects. This was shown in a paper where the authors report the results of perceptual experiments showing that depth discrimination under diffuse uniform sky lighting is superior to that predicted by a direct lighting model.<ref>{{cite journal|doi=10.1068/p3060|title=Depth discrimination from shading under diffuse lighting|first=M.S.|last=Langer|author2=H. H. Buelthoff|journal=Perception|volume=29|issue=6|pages=649–660|year=2000|pmid=11040949}}</ref>
<center>
{|
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</center>
 
The occlusion <math>A_\bar p</math> at a point <math>\bar p</math> on a surface with normal <math>\hat n</math> can be computed by integrating the visibility function over the hemisphere <math>\Omega</math> with respect to projected solid angle:
 
<center>
<!-- Unsourced image removed: [[Image:Aocclude hemisphere.png|none|400px|{{deletable image-caption|1=Saturday, 21 March 2009}}]] -->
</center>
 
<center>
<math>
A_\bar p = \frac{1}{\pi} \int_{\Omega} V_{\bar p,\hat\omega} (\hat n \cdot \hat\omega ) \, \operatorname{d}\omega
</math>
</center>
 
where <math>V_{\bar p,\hat\omega}</math> is the visibility function at <math>\bar p</math>, defined to be zero if <math>\bar p</math> is occluded in the direction <math>\hat\omega</math> and one otherwise, and <math>\operatorname{d}\omega</math> is the infinitesimal [[solid angle]] step of the integration variable <math>\hat\omega</math>. A variety of techniques are used to approximate this integral in practice: perhaps the most straightforward way is to use the [[Monte Carlo method]] by casting rays from the point <math>\bar p</math> and testing for intersection with other scene geometry (i.e., [[ray casting]]).  Another approach (more suited to hardware acceleration) is to render the view from <math>\bar p</math> by rasterizing black geometry against a white background and taking the (cosine-weighted) average of rasterized fragments. This approach is an example of a "gathering" or "inside-out" approach, whereas other algorithms (such as depth-map ambient occlusion) employ "scattering" or "outside-in" techniques.
 
In addition to the ambient occlusion value, a "bent normal" vector <math>\hat{n}_b</math> is often generated, which points in the average direction of unoccluded samples.  The bent normal can be used to look up incident [[radiance]] from an [[environment map]] to approximate image-based lighting. However, there are some situations in which the direction of the bent normal is a misrepresentation of the dominant direction of illumination, e.g.,
 
<center>
[[Image:Aocclude bentnormal.png|none|thumb|400px|In this example the bent normal N<sub>b</sub> has an unfortunate direction, since it is pointing at an occluded surface.]]
</center>
 
In this example, light may reach the point p only from the left or right sides, but the bent normal points to the average of those two sources, which is, unfortunately, directly toward the obstruction.
 
==Recognition==
In 2010, Hayden Landis, Ken McGaugh and Hilmar Koch were awarded a [[Scientific and Technical Academy Award]] for their work on  ambient occlusion rendering.<ref>[http://www.altfg.com/blog/awards/oscar-2010-scientific-and-technical-awards-489/ Oscar 2010: Scientific and Technical Awards], ''Alt Film Guide'',  Jan 7, 2010</ref>
 
==See also==
* [[Global illumination]]
* [[Photon mapping]]
* [[Radiosity (3D computer graphics)|Radiosity]]
* [[Ray tracing (graphics)|Ray tracing]]
* [[Reflection occlusion]]
* [[Screen space ambient occlusion]]
 
==References==
<references/>
 
==External links==
* [http://www.andrew-whitehurst.net/amb_occlude.html Depth Map based Ambient Occlusion]
* [http://research.nvidia.com/publication/ambient-occlusion-volumes NVIDIA's accurate, real-time Ambient Occlusion Volumes]
* [http://www.cs.unc.edu/~coombe/research/ao/ Assorted notes about ambient occlusion]
* [http://www.tml.hut.fi/~janne/aofields/ Ambient Occlusion Fields] — real-time ambient occlusion using cube maps
* [http://research.nvidia.com/publication/pantaray-fast-ray-traced-occlusion-caching-massive-scenes PantaRay ambient occlusion used in the movie Avatar]
* [http://hal.inria.fr/inria-00379385 Fast Precomputed Ambient Occlusion for Proximity Shadows] real-time ambient occlusion using volume textures
* [http://download.nvidia.com/developer/GPU_Gems_2/GPU_Gems2_ch14.pdf Dynamic Ambient Occlusion and Indirect Lighting] a real time self ambient occlusion method from Nvidia's GPU Gems 2 book
* [http://http.developer.nvidia.com/GPUGems3/gpugems3_ch12.html GPU Gems 3 : Chapter 12. High-Quality Ambient Occlusion]
* [http://vcg.sourceforge.net/index.php/ShadeVis ShadeVis] an open source tool for computing ambient occlusion
* [http://www.xnormal.net xNormal] A free normal mapper/ambient occlusion baking application
* [http://www.mrbluesummers.com/893/video-tutorials/baking-ambient-occlusion-in-3dsmax-monday-movie 3dsMax Ambient Occlusion Map Baking] Demo video about preparing ambient occlusion in 3dsMax
 
[[Category:Shading]]
[[Category:Global illumination algorithms]]

Latest revision as of 15:01, 2 December 2014

It is very common to have a dental emergency -- a fractured tooth, an abscess, or severe pain when chewing. Over-the-counter pain medication is just masking the problem. Seeing an emergency dentist is critical to getting the source of the problem diagnosed and corrected as soon as possible.

Here are some common dental emergencies:
Toothache: The most common dental emergency. This generally means a badly decayed tooth. As the pain affects the tooth's nerve, treatment involves gently removing any debris lodged in the cavity being careful not to poke deep as this will cause severe pain if the nerve is touched. Next rinse vigorously with warm water. Then soak a small piece of cotton in oil of cloves and insert it in the cavity. This will give temporary relief until a dentist can be reached.

At times the pain may have a more obscure location such as decay under an old filling. As this can be only corrected by a dentist there are two things you can do to help the pain. Administer a pain pill (aspirin or some other analgesic) internally or dissolve a tablet in a half glass (4 oz) of warm water holding it in the mouth for several minutes before spitting it out. DO NOT PLACE A WHOLE TABLET OR ANY PART OF IT IN THE TOOTH OR AGAINST THE SOFT GUM TISSUE AS IT WILL RESULT IN A NASTY BURN.

Swollen Jaw: This may be caused by several conditions the most probable being an abscessed tooth. In any case the treatment should be to reduce pain and swelling. An ice pack held on the outside of the jaw, (ten minutes on and ten minutes off) will take care of both. If this does not control the pain, an analgesic tablet can be given every four hours.

Other Oral Injuries: Broken teeth, cut lips, bitten tongue or lips if severe means a trip to a dentist as soon as possible. In the mean time rinse the mouth with warm water and place cold compression the face opposite the injury. If there is a lot of bleeding, apply direct pressure to the bleeding area. If bleeding does not stop get patient to the emergency room of a hospital as stitches may be necessary.

Prolonged Bleeding Following Extraction: Place a gauze pad or better still a moistened tea bag over the socket and have the patient bite down gently on it for 30 to 45 minutes. The tannic acid in the tea seeps into the tissues and often helps stop the bleeding. If bleeding continues after two hours, call the dentist or take patient to the emergency room of the nearest hospital.

Broken Jaw: If you suspect the patient's jaw is broken, bring the upper and lower teeth together. Put a necktie, handkerchief or towel under the chin, tying it over the head to immobilize the jaw until you can get the patient to a dentist or the emergency room of a hospital.

Painful Erupting Tooth: In young children teething pain can come from a loose baby tooth or from an erupting permanent tooth. Some relief can be given by crushing a little ice and wrapping it in gauze or a clean piece of cloth and putting it directly on the tooth or gum tissue where it hurts. The numbing effect of the cold, along with an appropriate dose of aspirin, usually provides temporary relief.

In young adults, an erupting 3rd molar (Wisdom tooth), especially if it is impacted, can cause the jaw to swell and be quite painful. Often the gum around the tooth will show signs of infection. Temporary relief can be had by giving aspirin or some other painkiller and by dissolving an aspirin in half a glass of warm water and holding this solution in the mouth over the sore gum. AGAIN DO NOT PLACE A TABLET DIRECTLY OVER THE GUM OR CHEEK OR USE THE ASPIRIN SOLUTION ANY STRONGER THAN RECOMMENDED TO PREVENT BURNING THE TISSUE. The swelling of the jaw can be reduced by using an ice pack on the outside of the face at intervals of ten minutes on and ten minutes off.

If you have any issues concerning the place and how to use Dentists in DC, you can speak to us at our own web site.