Search found 29 matches

by Geometrian
Thu Aug 14, 2014 3:51 am
Forum: General Development
Topic: Agreement of Light Tracing and Path Tracing with a Thin Lens
Replies: 3
Views: 2659

Re: Agreement of Light Tracing and Path Tracing with a Thin

My concern here is that the results from the path tracer and the results from the light tracer disagree.
by Geometrian
Thu Aug 14, 2014 3:30 am
Forum: General Development
Topic: Agreement of Light Tracing and Path Tracing with a Thin Lens
Replies: 3
Views: 2659

Agreement of Light Tracing and Path Tracing with a Thin Lens

Hi, I have implemented a light tracer and a path tracer. For every scene I have tried with a finite-aperture camera containing no lens (i.e., the aperture is just a hole) and a single light, the results match exactly. However, if a thin lens is added, the results differ. Specifically: --If the senso...
by Geometrian
Tue Aug 05, 2014 4:56 am
Forum: General Development
Topic: Monte Carlo Forward/Backward Radiance in Basic Example
Replies: 4
Views: 3885

Re: Monte Carlo Forward/Backward Radiance in Basic Example

I think I understand it now. It's literally exactly the same integral , just with the role of emitter and collector switched. Just as there is no extra cosine weighting needed when an eye-traced ray accumulates radiance from a light, there is no extra cosine weighting needed when a light-traced ray ...
by Geometrian
Thu Jul 31, 2014 10:47 pm
Forum: General Development
Topic: Monte Carlo Forward/Backward Radiance in Basic Example
Replies: 4
Views: 3885

Monte Carlo Forward/Backward Radiance in Basic Example

I have the following simple example: --Sensor: 1 square meter panel, records radiant flux ϕ --Light: 1 square meter panel, Lambertian (constant radiance) emission of L=1.0. --The sensor and light are directly adjacent to each other. You can think of this a sensor plate and a light plate stuck togeth...
by Geometrian
Fri Jul 11, 2014 6:42 pm
Forum: General Development
Topic: Correct Weighting for all Camera Effects
Replies: 0
Views: 8858

Correct Weighting for all Camera Effects

Hi, This post intends to be a summary of all the issues I am currently working on. Any input anyone can provide would be welcome. I am currently restricting to area light sources and finite-aperture lenses. The camera model I am using is a circular thin lens with an image plane behind it. The image ...
by Geometrian
Wed Jul 09, 2014 5:24 pm
Forum: General Development
Topic: Weighting Paths in Light Tracing
Replies: 1
Views: 2409

Weighting Paths in Light Tracing

Hi, I have implemented a light tracer: random light paths are generated, and bounce around until they hit the camera lens, at which point they refract deterministically onto the image plane. I do not know how to weight these paths properly. I understand that one should divide by the number of light ...
by Geometrian
Mon Jul 07, 2014 2:49 pm
Forum: General Development
Topic: Camera Weighting in Eye Tracing
Replies: 10
Views: 6591

Re: Camera Weighting in Eye Tracing

I believe I have figured it out myself. To figure out the total power hitting a point on the image sensor, you need to figure out the integral of the radiance hitting it. For Monte Carlo, this is just your radiance estimate (one ray from image sensor to light) divided by the pdf (for evenly sampled ...
by Geometrian
Mon Jul 07, 2014 6:53 am
Forum: General Development
Topic: Camera Weighting in Eye Tracing
Replies: 10
Views: 6591

Re: Camera Weighting in Eye Tracing

I . . . understand that. You can send as many photons as you like. That's not the issue though. The issue is that aperture size and shutter speed affect brightness. This is true for virtual cameras too. It has nothing to do with how many paths you trace or how many exist. Here's a decent image: http...
by Geometrian
Mon Jul 07, 2014 6:39 am
Forum: General Development
Topic: Camera Weighting in Eye Tracing
Replies: 10
Views: 6591

Re: Camera Weighting in Eye Tracing

Why would the exposure time be infinite because the camera is a pinhole ? Think about it this way: the larger the aperture, the more paths there are more light to hit the sensor. For a true pinhole camera, there is only one light path that hits each point on the sensor. This is why real "pinho...

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