mirrors don't seem to be reflecting as they should - AccuRender nXt2024-03-28T14:35:10Zhttp://accurender.ning.com/forum/topics/mirrors-don-t-seem-to-be-reflecting-as-they-should?commentId=6293855%3AComment%3A43217&x=1&feed=yes&xn_auth=noTake the color and divide by…tag:accurender.ning.com,2011-08-19:6293855:Comment:432172011-08-19T23:00:29.444ZRoy Hirshkowitzhttp://accurender.ning.com/profile/RoyHirshkowitz
<p>Take the color and divide by 255. Square the result.</p>
<p> </p>
<p>r = (c/255)^2</p>
<p> </p>
<p>Use gray colors to make your life easier. Make sure the surface for which you are calculating the illuminance from the nXt luminance has a matte material (Highlight Intensity = 0.0). </p>
<p> </p>
<p>Take the color and divide by 255. Square the result.</p>
<p> </p>
<p>r = (c/255)^2</p>
<p> </p>
<p>Use gray colors to make your life easier. Make sure the surface for which you are calculating the illuminance from the nXt luminance has a matte material (Highlight Intensity = 0.0). </p>
<p> </p> maybe it's an area of market…tag:accurender.ning.com,2011-08-19:6293855:Comment:432162011-08-19T22:09:55.622Zcharlie bakerhttp://accurender.ning.com/profile/charliebaker
<p>maybe it's an area of market expansion once people know about the gaps in the industry software, <he suggested hopefully></p>
<p>in the meantime how to i calculate the reflectance?</p>
<p>thanks</p>
<p>maybe it's an area of market expansion once people know about the gaps in the industry software, <he suggested hopefully></p>
<p>in the meantime how to i calculate the reflectance?</p>
<p>thanks</p> Caustics paths are difficult…tag:accurender.ning.com,2011-08-19:6293855:Comment:430242011-08-19T17:49:06.044ZRoy Hirshkowitzhttp://accurender.ning.com/profile/RoyHirshkowitz
<p>Caustics paths are difficult to do properly and can be very time consuming. Modern software like <em>Maxwell</em> can handle these paths very well (although slowly)-- some older software such as <em>Radiance</em> could do some of them as well with some added user intervention.</p>
<p>Most lighting analysis software is really only set up for diffuse reflection. They can calculate this fairly quickly, and it is adequate for things like code-compliance simulations. This will change in the…</p>
<p>Caustics paths are difficult to do properly and can be very time consuming. Modern software like <em>Maxwell</em> can handle these paths very well (although slowly)-- some older software such as <em>Radiance</em> could do some of them as well with some added user intervention.</p>
<p>Most lighting analysis software is really only set up for diffuse reflection. They can calculate this fairly quickly, and it is adequate for things like code-compliance simulations. This will change in the future, no doubt.</p>
<p>*****</p>
<p>I can easily produce false color images of Luminance. I can't do Illuminance easily without making some changes to the engine. (Illuminance information was generated automatically in previous versions when using radiosity (not for caustics, though)). There isn't a lot of demand for lighting analysis tools-- I think yours is the second request I've had.</p>
<p> </p> much as i thought, but though…tag:accurender.ning.com,2011-08-19:6293855:Comment:430232011-08-19T17:38:57.194Zcharlie bakerhttp://accurender.ning.com/profile/charliebaker
<p>much as i thought, but thought i'd better check, i gave my agronomist the proportional difference between the direct and reflected for now, i'll leave PT running overnight to smooth out the variations, as i'd used a smooth material. but at risk of further exposing my lack of knowledge in this area, and i did try googling first to try and avoid having to ask yet more, how do you work out reflectance from the colours?</p>
<p>(i do quite the like the fact that urbed (staff numbers -9) and…</p>
<p>much as i thought, but thought i'd better check, i gave my agronomist the proportional difference between the direct and reflected for now, i'll leave PT running overnight to smooth out the variations, as i'd used a smooth material. but at risk of further exposing my lack of knowledge in this area, and i did try googling first to try and avoid having to ask yet more, how do you work out reflectance from the colours?</p>
<p>(i do quite the like the fact that urbed (staff numbers -9) and mcneel (staff numbers about 50 isn't it?) have managed to resolve an issue that IES and Ecotect and Buro Happold - (staff numbers massive) haven't.)</p>
<p>what we're all wondering is how do you do light shelves properly on other software if you can't reflect more than once. but also what is the bounces setting in accurender that you can set actually doing?</p>
<p>will this exercise make it worthwhile considering putting the lighting analysis from previous versions into net? that would complete the supremacy of net over the above.</p>
<p>thanks for your help so far</p>
<p> </p> Sorry for the late response--…tag:accurender.ning.com,2011-08-19:6293855:Comment:433212011-08-19T16:18:47.534ZRoy Hirshkowitzhttp://accurender.ning.com/profile/RoyHirshkowitz
<p>Sorry for the late response-- I was out of town for a few days. The mouse-over shows luminance. Luminance is the amount of light reflected back toward the viewer. It is definitely dependent on both the received light and the reflective properties (material) of the surface in question. Illuminance, on the other hand, is the amount of light received by a surface and is not affected by the material. Calculate illuminance from luminance using the procedure above.</p>
<p>The three values are…</p>
<p>Sorry for the late response-- I was out of town for a few days. The mouse-over shows luminance. Luminance is the amount of light reflected back toward the viewer. It is definitely dependent on both the received light and the reflective properties (material) of the surface in question. Illuminance, on the other hand, is the amount of light received by a surface and is not affected by the material. Calculate illuminance from luminance using the procedure above.</p>
<p>The three values are for each RGB channel-- they'll be the same if your material is gray.</p>
<p>The different values can be due to material variations (bumps, etc..) or to noise in the Path Tracer. The PT noise will eventually resolve, the variability in the material will not.</p> this is getting there now - i…tag:accurender.ning.com,2011-08-13:6293855:Comment:419192011-08-13T17:12:59.380Zcharlie bakerhttp://accurender.ning.com/profile/charliebaker
<p>this is getting there now - image attached, haven't remodelled mirror steelwork yet - , the geometry is quite fiendish trying to work out optimal mirror shape.</p>
<p>just a couple of things, i've checked the 2 units variable in autocad and they're both showing up as metres - you mentioned in your first reply that you had to change them to get the materials to render properly - am i missing a setting somewhere?</p>
<p> </p>
<p>on the mouse over illuminance - is that the 3 values at the…</p>
<p>this is getting there now - image attached, haven't remodelled mirror steelwork yet - , the geometry is quite fiendish trying to work out optimal mirror shape.</p>
<p>just a couple of things, i've checked the 2 units variable in autocad and they're both showing up as metres - you mentioned in your first reply that you had to change them to get the materials to render properly - am i missing a setting somewhere?</p>
<p> </p>
<p>on the mouse over illuminance - is that the 3 values at the bottom of the render window? if so;</p>
<p>q1 how come there are 3 of them?</p>
<p>q2 how come the value changes so radically if i change materials, i'd have thought luminance was the amount landing there so not connected to what it was landing on?q2a if it is dependent on the material, how do i calculate the reflectance from the colour?</p>
<p>q3 there are quite a lot of different values as i mouse over the single area - so do i need to make the floor a single texture free colour to even those out?</p>
<p> </p>
<p>sorry for being so thick!</p>
<p>but thanks for your help - we're only a little practice and we have managed to do what a major corporate engineering company we were told to work with couldn't - they were using IES so i've had to do it for them using your, as ever, marvellous software</p> By reflectance I wast just re…tag:accurender.ning.com,2011-08-09:6293855:Comment:400852011-08-09T12:08:58.155ZRoy Hirshkowitzhttp://accurender.ning.com/profile/RoyHirshkowitz
<p>By reflectance I wast just referring to the color. I made the mirror color 253,253,253 instead of 180. Not sure why you see only one response-- the second picture is better. </p>
<p> </p>
<p>No illuminance data directly. By running your cursor over the image you can get luminance (in cd/m^2). You can calculate illuminance (lux) for any matte surface by taking that luminance number, multiplying by the reflectance (calculate that from the color as mentioned above)-- and divide by PI.</p>
<p>By reflectance I wast just referring to the color. I made the mirror color 253,253,253 instead of 180. Not sure why you see only one response-- the second picture is better. </p>
<p> </p>
<p>No illuminance data directly. By running your cursor over the image you can get luminance (in cd/m^2). You can calculate illuminance (lux) for any matte surface by taking that luminance number, multiplying by the reflectance (calculate that from the color as mentioned above)-- and divide by PI.</p> you're a star thanks for the…tag:accurender.ning.com,2011-08-08:6293855:Comment:407022011-08-08T21:39:17.760Zcharlie bakerhttp://accurender.ning.com/profile/charliebaker
<p>you're a star thanks for the first reply - i can see the outline now but in your other reply which showed up on my mail doesn't seem to show up here, you mentioned the reflectance but i can't seem to find the setting in the material editor which makes me feel a bit daft</p>
<p> </p>
<p>also once i've got this working, will i be able to pull up a lighting analysis graphic with the false colours like the old accurender used to to do?</p>
<p> </p>
<p>if not will i be able to pull of lighting…</p>
<p>you're a star thanks for the first reply - i can see the outline now but in your other reply which showed up on my mail doesn't seem to show up here, you mentioned the reflectance but i can't seem to find the setting in the material editor which makes me feel a bit daft</p>
<p> </p>
<p>also once i've got this working, will i be able to pull up a lighting analysis graphic with the false colours like the old accurender used to to do?</p>
<p> </p>
<p>if not will i be able to pull of lighting values any other way - the agronomists need to know lux levels for plant growth.</p>
<p> </p>
<p>thanks in advance</p> BTW, your metal material is…tag:accurender.ning.com,2011-08-06:6293855:Comment:403202011-08-06T21:39:48.884ZRoy Hirshkowitzhttp://accurender.ning.com/profile/RoyHirshkowitz
<div class="description xj_comment_editor" id="desc_6293855Comment40401"><p>BTW, your metal material is only 50% reflective or so. That means the double bounce will only be about 25% reflective. When I change the material color to 253 253 253 (a reflectivity of about 98.4%), I get a very different result. You'll need to calibrate this value carefully to the actual material if you want to get a good simulation. To get the reflectivity from the color, divide by 255 and square the result. To…</p>
</div>
<div class="description xj_comment_editor" id="desc_6293855Comment40401"><p>BTW, your metal material is only 50% reflective or so. That means the double bounce will only be about 25% reflective. When I change the material color to 253 253 253 (a reflectivity of about 98.4%), I get a very different result. You'll need to calibrate this value carefully to the actual material if you want to get a good simulation. To get the reflectivity from the color, divide by 255 and square the result. To get a color from reflectivity, take the square root and multiply by 255.</p>
<p> </p>
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</ul> First of all, the units are i…tag:accurender.ning.com,2011-08-06:6293855:Comment:397982011-08-06T21:15:25.736ZRoy Hirshkowitzhttp://accurender.ning.com/profile/RoyHirshkowitz
<p>First of all, the units are incorrect. I changed the units to meters to better match the scale of the model. Always check this first, it was causing your textured columns to be rendered incorrectly. Now, on to the real problem:</p>
<p> </p>
<p>Bouncing light of a mirror-like surface to illuminate other surfaces is what's known in rendering as a <em>reflective caustics</em> path. It is a very difficult problem for rendering software to handle. It was not handled at all by previous version…</p>
<p>First of all, the units are incorrect. I changed the units to meters to better match the scale of the model. Always check this first, it was causing your textured columns to be rendered incorrectly. Now, on to the real problem:</p>
<p> </p>
<p>Bouncing light of a mirror-like surface to illuminate other surfaces is what's known in rendering as a <em>reflective caustics</em> path. It is a very difficult problem for rendering software to handle. It was not handled at all by previous version of AR. In nXt it is possible to do, although it's not perfect (it doesn't work well for all models) and you do need to do a little work in terms of telling nXt which surfaces to consider. It does work better with the Path Tracer.</p>
<p> </p>
<p>I did the following:</p>
<p> </p>
<ol>
<li>I switched to the Path Tracer in Lighting->Advanced.</li>
<li>I exploded the block containing the outside solar reflectors.</li>
<li>I selected the reflectors and tagged them as <em>Caustics</em> using the Object Properties tab. It is not necessary to select the ceiling reflector since it doesn't receive light directly.</li>
<li>I let the thing render for about ten minutes.</li>
</ol>
<p>You can pretty clearly see the additional light in the first image (the second has no caustics.) In particular, the reflected light on the floor from the ceiling shows up as a discrete rectangle (expected with a mirror-like surface.) There is also a rectangular reflection on the ceiling.</p>
<p> </p>
<p> </p>
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