Dark Rendering

[Tony Weddle]

I did search for this problem but couldn't find one that fits, so apologies if it has already been covered.

A lot of my 3D real view rendering is very dark. It definitely isn't a real view. For example, I'm trying to find out how a  bathroom on the south side (in the southern hemisphere) looks at around 1pm on the shortest day (in June). This is similar to the date right now and our current bathroom, on the south side, is way, way brighter than the rendered 3D view. Through the window, you can see sunlight casting shadows, so there should be plenty of ambient light to light up the bathroom (as per our real life bathroom). The basic rendered view isn't too bad but the advanced view is terrible, as attached. I have no inside lights yet, "Use current time for rendering" is switched off, quality level is set to "high", number of steps is 500 and Antialiasing is set to 4. Rooms on the north side are much better but still darker than I would expect.

Any ideas?

Tony

[Allan Chesney]

Hi Tony,

First I would suggest that you check the Transparency setting for the glass in the window, as even the sky looks a bit dark. Mine is 90% and no Specular (reflection).

The other thing I would suggest is to use the highest quality setting (1500 steps).

Rendering does require some experimenting and there are many things that can affect lighting in Real View (as well as in real life.) I have tried to replicate your model to illustrate.

1. The first image is much like what you got - 500 steps.

2. This was rendered on the highest quality setting - 1500 steps.

3. This is identical settings to 2, except that the window has been Flipped, so it has a window ledge on the inside rather than outside, like yours (Note how much lighter it is, as the light on the window ledge is bounced around the room).

4. The last image is the same but has some light coloured paving below the window on the outside (Note the extra light on the ceiling reflected off the paving).

The Sky (background image) does not emit light (unlike a real one) so the only light going through a shaded window, is from reflection off outside surfaces - the outside wall and the window in it (this contributes quite a bit), the window ledge itself and the terrain, which is why the light coloured paving under the window brightened things even more.

I hope this helps you to get a bit more Real View 

Allan

[Tony Weddle]

Thanks for taking the time to check this, Allan. I wish I was using your system because the changes made no discernible difference to my rendered view, and I even used the highest quality setting, taking nearly 5 minutes to render (it's a shame it can't make use of the other 3 CPUs I have).

I've attached the basic rendering, the advanced rendering with 1500 steps and highest quality setting, and the same again but with window glass instead of semi-transparent glass. It's difficult to see a difference between the last two but the first basic rendering actually lets me see the bathroom.

I didn't mess with the brightness setting as the help suggests that leaving it at zero works like a camera which automatically adjusts for the light.

Even if I got the rendering to be as bright as yours, I wouldn't now know which rendering is "real" and so wouldn't be able to determine if the design I'm working on would actually work.

One thing I didn't mention was that there is a projecting wall on the other side that can't be seen through the window at that angle. This is similar to what we are actually living in now and there is no problem with the light but what I was hoping to check is whether a roof connecting both projecting walls would significantly impact the light. The views attached don't have that roof but I've tried with and without a roof and it makes no difference to the rendered view.

Is the basic rendering reasonably accurate, light-wise?

[Allan Chesney]

Hi Tony,

I realised that you have a wall that was not visible (I noticed the shadow of it) so I had also included that. I have now rendered the image again with a roof between the two walls and, as you can see, the difference is negligible as you found. When you see the two images side by side they look identical. When you flip from one to the other in a folder, you can see the ceiling is slightly darker, as is the right hand wall, which gets reflection from the ouside wall on the left. However, in the real world, most of the light into this room would be from the sky. As I mentioned before, the TFP sky does not emit light, so it does not really replicate the real world very well, relying, in your view, on reflected light from other exterior surfaces. When the sun is actually shining into the room the 'reality' of it would be much closer. The Basic render would not be a good representation of reality either, as it does not take any notice of reflected light at all, as does Advanced render, so the lighting in Basic render is largely an 'example' rather than a reality.

I am not sure why yours is rendering so dark. Other things can affect it and the only way to check would be or me to have a look at it, try rendering your specific model and see if I get the same result (and if I can find a reason). I don't think my computer is the reason, as it is not particularly high spec. My Advanced render took less than 2 minutes, but my model was just one room and a couple of extra walls - yours was the whole building which would take much longer. Advanced renders the whole building unlike Basic which ignores the rest and just renders the camera angle. If your model is small enough you may like to post the BLD file here or if you prefer you can email it to me.

You can play with the brightness setting, it won't prevent the 'automatic camera' effect, it will just make it lighter, as if you had changed the camera settings, to simuate using a more sensitive film. You should end up with a lighter image, but that will obviously not really give you any idea of the true brightness of such a room.

None of of the above really helps with your delemma and maybe TFP is not really the program on which to base a decision. If your existing bathroom is a similar situation, then I would use that as a guage and maybe even rig up a tarpaulin or something to see how much a roof would reduce the light. Quite a bit I suspect. At the same time, you do not spend a long time in a bathroom (unless you have a wife and many daughters  ), so use of artificial light for those occasions should not add a lot to the power bill. Having the area roofed, depending why you want it, may be well worth the slight electricity increase.

If you would like me to check out the model for you, my email is alches AT iinet DOT net DOT au.

Allan

[Tony Weddle]

Allan,

Thanks for the reply and the suggestions. Yeah, I guess RealView isn't "real", so far as ambient light is concerned. I guess that's fair, as it would be pretty hard to program in what was happening to the light outside before it entered the room.

Given that I won't get a realistic view of the bathroom, I don't think it's necessary for you to look into this any further, but thanks for the offer (I'll keep it in mind). The idea of tarp over the walls is not a bad idea and I might just do that.

Thanks again.
Tony

[Doug.S]

I'd think you might want to know this info too:  (but it also depends on what "look/result" you are trying to achieve)

- Interior lighting is best achieved with lights also included inside...otherwise you are counting on outside lighting to light an interior which in real life is often not very bright unless there are many large windows.  (In which case you might want to turn off the sun light.)

- or consider adding outside lights which provide more light thru the window but are not seen.

- Yes, being a 32bit program and not optimized for hyper-threading and multi CPUs, TFP could be much faster. Try both renders (basic and advanced) as the results differ . . . . and you will find that using advanced renders, the second render pass (same as basic pass; raytracing) uses all cores (in my case, eight). . . . so the adv result may not take too long compared to basic.
Although in basic renders, only 1 core is used....why? I have no clue why they programmed it that way; seems dumb to me.

I have done many studies of sunlight thru windows at various times of the year and found TFP to be a bit lacking. My approach was to "build" the house in TFP and export as a 3D model, import to another 3D program (I used Carrara) and made videos of sunrise thru sunset. Carrara sun controls are far superior and the sunlight is even corrected for color changes from dawn to dusk. Shadows have many controls too.  Blender is a free program that will do same.
Also of small note is that TFP shadows render slightly differently in basic vs. adv.  (angles differ).

[Tony Weddle]

Thanks for the comments, Doug.

Since most of the time is spent in radiosity, with advanced rendering, I don't think the fact that raytracing uses all cores will save a noticeable amount of time, except in lower resolutions or a low number of steps.

I realise that inside lights would give me a brighter picture but I was really after a view with only natural light from the sun (if indirectly). I realise now that that is probably too much of an ask for a fairly inexpensive product (though I would guess that there is probably some well understood way of calculating how much daylight would enter a particularly sized window that wasn't directly in the sunlight).

I suppose that a separate program is an option but that is quite an expensive option compared to rigging a tarp over my existing courtyard!

[Allan Chesney]

Hi Tony,

I don't know whether you know this or not but if you do an Advanced render, you can create multiple image from the one render, so if it takes a while it does not really matter. When you do an Advanced render, it calculates the shadows and reflected light for everything - not just what that particular camera sees. So, once the first image has been produced, you can select the Radiosity button and then move the camera and take as many images as you want. It only takes seconds to produce these further images all from the original radiosity render. If you close the dialog box, then you will have to do the radiosity phase again.

I am concerned why you image is coming out so dark. Even if it not practical to use TFP to see how bright the bathroom would be, you should still be able to see it and get some idea how things will look. I feel that something else is affecting the render, so, if you would like, I would not mind looking at it anyway, to see if I can find out why.

Allan

[Doug.S]

Yes, I just remembered another trick....if an image is too dark you can do post render work. 

The best is Photoshop (make a copy layer and set it to "multiply") and there are many other ways to get brighter, better images with better contrast, clarity, color, sharpness etc.

You can do a lot with almost any image editing s/w. Free, GIMP, can do great stuff too.

[Tony Weddle]

Thanks for the tips, Doug. I'll keep them in mind.

And thanks to Allan regarding the fact that the radiosity calculations are for the whole building. It's quite cool to be able to move around in fairly high resolution.

I've sent Allan my bld file to see if he can spot why it's rendering so darkly. However, this design has been through many iterations and I've now seen a better way to arrange the rooms, which doesn't have the potential issue of a roof over the rear courtyard blocking light to the bathroom. So I'm not so concerned but, as this progresses, I will be checking back on these tips to get some good views inside the house.

[Doug.S]

And thanks to Allan regarding the fact that the radiosity calculations are for the whole building. I will be checking back on these tips to get some good views inside the house.

My approach to rendering several views (as well as used for design work) is to insert several cameras, each named for a view, and using the view manager to create a tabbed view (always 1 for floorplan and as many others for 3D as needed).
There are 3 big advantages: 1) able to render repeatable same views for comparisons  2) named cameras listed for easy adv renders 3) easy to jump between views.

In the render dialog box, once the first adv/radiosity render completes (I always set to do follow-on auto raytrace too)...without closing the render window, you can select another camera view from drop down list) . . . and these renders go fast with raytrace done with all cores and no re-do of radiosity.

see attached screen grabs from current active project

[Tony Weddle]

Thanks for that tip, Doug.

I've now redrawn my design, adding some internal lights. Rendering is fine with lights on but still dark with just daylight. For example, this is the main room of the house, with daylight switched on (which seems to turn off the internal lights for advanced rendering, which is fine). Time is noon on the shortest day of the year, so lots of sunlight should be coming in. In my current actual home, the main room has less windows, though similar proportion, I'd say, and it's cloudy, at 3 in the afternoon, but the light is way better than the rendered image of the new design. I have the number of steps set to 500 and the brightness set to 1.0. It was much darker with the number of steps set to 200, so I guess I could just about manage to get a bright image with many more steps and brightness notched up more but surely this should be a lot better, even with default settings? I also notice that the default wall coverings appear to be a gloss finish (you can just make out reflections next to the table here but some reflections I've seen are almost mirror like, when reflecting sunlit surfaces). This seems bizarre for wall finishes but now I've got lots of wall sections with gloss paint, effectively; what's the easiest way to get a matt finish for all internal surfaces?

[Allan Chesney]

Hi Tony,

The only way to get a decent render internally is to set the quality to max (5) and 1500 steps. Use a very small size image to save render time and check for brightness. When satisfied make the size larger.  Most of the lightening occurrs in the final steps. To render internal views with lights on, turn daylight off. Daylight will turn interior lights off.

Some texture do default to gloss and gloss surfaces will increase render time and affect lighting results too. I only use gloss on obvious surfaces (glass, polished timber etc) and only a small amount (Speculation setting 1-5% only) .

The gloss level is changed in the materials library on the Properties / Appearance tab, but you need to change this before using the texture. It will not update textures already used in the model. to change existing ones you can select a wall, right click and Select All Similar then right click again and go to Properties and change the setting (click the texture image and then tick the Display box at the bottom). The Specular slider will change the setting on all the walls selected but be careful if you have other rooms with different textures on the opposite side of the wall. The left and right side of the wall is in relation to how it was drawn, where the green wall end marker is where you started and red where you finished.

Let me know how you go.

Allan

[Tony Weddle]

Let me know how you go.

Not very well.  I think I might have to give up the idea as I'm fighting against the program.

I got a reasonable rendering but forgot to change the wall paint to a matt finish. So I did that, saved to a different file and then tried to render on the highest resolution. The program stalled. After a restart, I tried again on a slightly lower resolution (high) but got an object parsing error. It seemed to be the floor but I couldn't figure out what it was complaining about. Then the previous design file started getting object failures. I thought it might be some wall joins, where I got an internal wall to join flush with an outside wall. That seemed to fix it when I tried on a low resolution but when I went up to higher resolution, the object parsing error came back, even though I didn't change anything in the design. I just gave up - it's taking far too much time. I tried repairing, shifting walls and floors but nothing worked, so I'll have to make do with the normal program 3D view, unless I've got oodles of time later to do the complete design again from scratch.

Thanks for your help.

[Allan Chesney]

Hi Tony,

If you are getting parsing errors there almost certainly a corruption somewhere and Advanced Render and higher resolutions will complain! You mentioned you suspected a Floor issue. Did you delete and replace it? The way to test is to turn everything on in View Filter then turn off all floors and render. If it works the floor is the problem. If it fails again turn floors back on and turn off walls and render again. This way you find the group of objects with the problem. If you have other Locations then you can filter them out also.

Send me the file if you would like me to check it out. Would be quicker than starting again.

Allan