[Jonathan B]

I have recently been using the maxwell plug-in for sketchup to expand my rendering skills, yet i believe i'm a fair way away from mastering this programme! I have bought the plug-in (and have a 30 day trial for the studio) and have got some basics sorted.

However, I've already discovered that something can't be quite right as I have had to use about 80 LEM's (400mm x 400mm) with a huge wattage (25,000 watts each) for a visual of a small speakers stage project. The scale of the drawing I think is right but the LEM quantity doesn't seem right. Perhaps this is also to do with there being no sunlight used, purely flat emitters.

The other issue which is really tackling my brain is how to get the gloss/ shimmer effect on materials so they have more reflectance. I have dropped the roughness to 0 and the nd around 2... how can get more of a shine without photoshopping!! I can't add extra layers or coatings in the plugin version can I?

I will attach a visual of the original render when someone can tell me how!! It's the white goalpost which i want shiny, and the overall lighting to be brighter. I was quite happy with the overall resolution (did it to max 1920 res) but have attached lower res jpeg.

Thank you

[JDHill]

I am not certain what you mean by LEM, but regarding the need to use unrealistic numbers of emitters and unrealistic emitter wattage, the first question is generally whether the model is to scale (and you indicate it is), the second, whether the efficacy is correct for the light type being simulated, and the third, whether the camera is using a suitable exposure for the situation. With those things in line, it should also be noted that light will propagate through the scene more completely as you pass through sampling levels (it should not get appreciably brighter after, say, SL 7 or so).

It is also not clear whether you are using 80 separate emitter materials, or are applying a given material to 80 different groups; if the former, then just be aware that this is not necessary, since a single emitter material will apply its specified wattage to each individual mesh to which it is applied. However, it should also be noted that it is also possible to create 80 faces which are either not grouped, or are all part of the same group; this produces a single mesh containing all the faces, in which case, the applied wattage will be spread across the total surface area.

Regarding roughness, Nd, and reflectance, in a lighting situation like the one you describe, overly-smooth materials may tend to appear too dark, since the lower the roughness, the more objects using the material tend to reflect in one direction only. Take it to the extreme: draw a box hanging in outer space, apply a perfect mirror material to it, and then shine a light on it. Unless your camera is situated just perfectly, you will see nothing; add some roughness, though, and light begins reflecting at random angles, allowing you to begin to see the box.

And regarding Nd, lowering this is not what you would want to do to increase the material's reflectivity; at higher Nd values, you get more reflection back from a surface perfectly facing the camera -- at Nd 1.0, you will get none. This is why you can see into a glass marble (Nd ~1.5); were the Nd too high, the glass would become more mirror-like, reflecting most light back at the camera. An Nd in the ~2.0 range is what allows you to, for example, see a red surface when looking directly at it (imagine something like a Formica countertop), where as you lower your viewing angle, you begin to see the environment being reflected instead.

Please let me know if you find this information helpful. Regarding the posting of images, to do this, you need to upload the image to a server somewhere (e.g. imageshack.us) and link to it in your post by using the [img][/img] bbcode tags (there is a button for it in the posting form).

[Jonathan B]

Thanks that is very helpful. By LEM i mean Light emitting material, a term i think i picked up using SU Podium to render. I have used one material as an emitter and applied it to the 80 no. approx individual faces. These are in groups of around 20 (angled around the stage) so i'm not sure if this creates a single mesh containing all the faces and therefore the wattage is evenly spread. I also have a few acting as spot lights which are visible in render...

See image:

Can I upload a model? Tried linking to my skydrive but dont think it allows other users in...

In response to your 3 questions: 1. The model is to scale, 100% sure. 2. I'm not sure what you mean by the efficacy, could you explain this further please? 3. The camera is on a manual setting, EV = 14, fStop = 5.6, shutter 522, ISO = 100.

I think I have too many smooth faces then by the sounds of it, I will try this mirror technique, I assume I can use a mirror material (from mxm material) and change it to white and play around with roughness/ nd values?

[Jonathan B]

Not sure if that link works? Try this...

[JDHill]

I have used one material as an emitter and applied it to the 80 no. approx individual faces. These are in groups of around 20 (angled around the stage) so i'm not sure if this creates a single mesh containing all the faces and therefore the wattage is evenly spread. I also have a few acting as spot lights which are visible in render...

Generally speaking, to create a single emitter object, I would draw a set of faces, group them, and apply an emitter material to the group (I avoid assigning materials to individual faces whenever possible, just because it keeps the model cleaner and easier to understand). A group or component containing faces will be exported as a single mesh, so it's still difficult to determine, from the above description, exactly how many meshes are being created. Groups and components also support Maxwell's "Hide from" flags (these are accessed via the group/component's context menu in SketchUp), allowing you to hide the emitter from the camera, for example.

Can I upload a model? Tried linking to my skydrive but dont think it allows other users in...

I am not familiar with skydrive, but many people use dropbox for this. If you upload the SKP and point out some specific issues you'd like to address (annotating them in the image you posted above), I can take a look and see if there are any specific problems happening with it.

2. I'm not sure what you mean by the efficacy, could you explain this further please?

An emitter material in Maxwell may have its output power determined in several different ways. Emitters created using the plugin's material editor (meaning, those which use the Emitter Character) use Watts and Efficacy. Watts is the input power, and Efficacy is the efficiency at which that power is converted to light by the emitter. The plugin's Emitter Character uses Watts & Efficacy because this information is commonly available from light manufacturers.

3. The camera is on a manual setting, EV = 14, fStop = 5.6, shutter 522, ISO = 100.

This exposure is suitable for broad daylight. The EV (Exposure Value) number indicates the overall exposure created by the combination of fStop, shutter, and film ISO. Without being directly able to change the EV, if you wished to alter the depth of field by adjusting the fStop, this would also alter your exposure, and you would need to compensate using shutter or ISO. Therefore, by default, the plugin locks exposure to the EV, allowing you to adjust depth of field via the fStop value, without altering the exposure, or vice versa, by directly adjusting the EV. A chart of EV numbers for common scenarios is available here. For the scene you depict above, I would probably use an EV in the 7-9 range, which you will see, will brighten the exposure considerably.

I think I have too many smooth faces then by the sounds of it, I will try this mirror technique, I assume I can use a mirror material (from mxm material) and change it to white and play around with roughness/ nd values?

I am not sure exactly what you are referring to here. Looking at the above image, I would not do much with the materials until I had played with the makeup of the emitter objects, and adjusted the exposure. When I was discussing overly-smooth materials above, I was thinking of, for example, some scenes I've seen with people rendering something like a tradeshow booth, where the booth is just sitting in the middle of a dark space. I don't think this applies very much to your particular scene.

[Jonathan B]

Ok so here is the model https://www.dropbox.com/home/LINKS?sele ... 0stage.skp

and annotated image http://img23.imageshack.us/img23/6147/s ... otated.jpg

In response to your helpful answers:

Generally speaking, to create a single emitter object, I would draw a set of faces, group them, and apply an emitter material to the group (I avoid assigning materials to individual faces whenever possible, just because it keeps the model cleaner and easier to understand). A group or component containing faces will be exported as a single mesh, so it's still difficult to determine, from the above description, exactly how many meshes are being created. Groups and components also support Maxwell's "Hide from" flags (these are accessed via the group/component's context menu in SketchUp), allowing you to hide the emitter from the camera, for example.

Each of my lights were one face each of 400x400mm size, and as a bunch of approx 20 I then grouped them.
I have been using the 'hide from' flags, as these emitters are all around the stage, so I had to make them invisible.

An emitter material in Maxwell may have its output power determined in several different ways. Emitters created using the plugin's material editor (meaning, those which use the Emitter Character) use Watts and Efficacy. Watts is the input power, and Efficacy is the efficiency at which that power is converted to light by the emitter. The plugin's Emitter Character uses Watts & Efficacy because this information is commonly available from light manufacturers.

This helps clear this up in my head!

This exposure is suitable for broad daylight. The EV (Exposure Value) number indicates the overall exposure created by the combination of fStop, shutter, and film ISO. Without being directly able to change the EV, if you wished to alter the depth of field by adjusting the fStop, this would also alter your exposure, and you would need to compensate using shutter or ISO. Therefore, by default, the plugin locks exposure to the EV, allowing you to adjust depth of field via the fStop value, without altering the exposure, or vice versa, by directly adjusting the EV. A chart of EV numbers for common scenarios is available here. For the scene you depict above, I would probably use an EV in the 7-9 range, which you will see, will brighten the exposure considerably.

I have just noticed that by playing around with the EV to around 8 that the overall scene is brighter. I have also been playing with the materials and using the predefined glossy materials and I can see them responding more to have that brighter look, as the emitters as very close to the front wall.

The other issue I have is with the studio version of maxwell (I have a 30 day trial). When I export my sketchup model It always seems to import my layers as materials, is this normal??

[JDHill]

Thanks, but I think you need to provide a different link to the file on dropbox (this one appears to be pointing somewhere in your own folder). You should be able to copy the file into C:\Users\[user name]\Dropbox\Public, then right-click on the file and choose Copy Public Link.

Each of my lights were one face each of 400x400mm size, and as a bunch of approx 20 I then grouped them. I have been using the 'hide from' flags, as these emitters are all around the stage, so I had to make them invisible.

In this case, you are going to have 20 meshes, each putting out the wattage defined in the emitter material they are assigned. More importantly though, I get the idea that you may be trying to bring strategies learned with another render engine over into Maxwell -- if so, it will be useful to know that this is usually not going to be the way to go. The lighting in your scene should be modeled very closely to how you would do it if lighting the scene for a photography shoot in real life. If you would have 80 fill lights, then you should do that, but if you're just doing this based on how you'd place area lights with another renderer, you may want to reconsider the strategy.

I have just noticed that by playing around with the EV to around 8 that the overall scene is brighter.

Yes, definitely. Probably the most important thing to understand about Maxwell is that it is primarily a very accurate camera simulator. You draw geometry, and set up emitters and materials, but you could consider those things as being secondary to what you are actually doing, which is taking a virtual photograph. This is fundamentally different than what you do with other renderers, and you'll increase your chances of success by really embracing the concept. It's hugely valuable, since for example, you do not need to learn anything that is specific to how Maxwell takes a picture -- you can learn everything you need to know about the camera by reading sources on general photography. What you learn there will apply to Maxwell...and vice versa.

I have also been playing with the materials and using the predefined glossy materials and I can see them responding more to have that brighter look, as the emitters as very close to the front wall.

As I alluded to above, if you are using dozens of fill lights, this is likely to greatly reduce any dramatic lighting effects, as compared to a scene that is set up to more closely mimic the real life situation. I haven't seen the model yet, but I wonder if there aren't so many of these lights set up that you are effectively filling in any possible shadow areas, and ultimately producing a result that is much flatter than what you are after. Looking over the annotations you included, the first question that comes to mind is: these objects are supposed to be more reflective, but what is it that they are to reflect? Having many fill lights will pretty much kill any dramatic highlights you'd otherwise have in the scene.

The other issue I have is with the studio version of maxwell (I have a 30 day trial). When I export my sketchup model It always seems to import my layers as materials, is this normal??

There is a "Color by Layer" option in the SketchUp layers window, whereby you can choose to export materials by layer, rather than as assigned by object (this only works with the Render Suite plugin, not the Standalone one), but I am not sure if this might be what you are referring to. I will be able to tell you more once I see the model.

[Jonathan B]

Sorry for slightly delayed response.

I think this link should now work for my model https://www.dropbox.com/s/03vnoesjlrba1 ... 0stage.skp

I definitely think I have brought in techniques from other rendering programs so will learn more of the fundamentals about photography.

Practise makes perfect I suppose so will keep testing out Maxwell with new models and no doubt be back on the board!

Do you think there are some major elements that I might be missing out on by just using the plugin version compared to the studio version of Maxwell? Or do you think I will be able to still obtain very high quality renders from the plugin alone? And in the plugin version, am I able to use all mxm materials from the maxwell website (to their full effect) that seem to work more seamlessly in the studio version? I'm very tempted to get the company i'm working for to buy full version but obviously want to know the limits of the plug in first!

[JDHill]

Thanks, I was able to download the file this time. Yes, definitely, the lighting technique there looks like something I'd expect to see being used with a renderer which does not deal with light & camera in a very physical way, as Maxwell does. I do not know exactly what the lighting in the room would be in reality, but I'll try to guess and modify it a bit, though I may not have time to do that until tomorrow.

Regarding the standalone plugin vs Maxwell Render Suite, you can indeed use all of the MXM materials from the plugin. For instance, your "high gloss laminate" material is set to use an MXM file. You can end up with a material like this in one of two ways: by using the "Browse for an MXM file" and "Browse the MXM Gallery" buttons in the plugin, or by selecting a material and switching it to use "MXM Mode", by toggling the "MXM" button at the top right of the material editor, and then browsing to an MXM file. What you cannot do is create or edit MXM files -- that requires Maxwell Studio, or the Maxwell MXED material editor, both of which are part of Maxwell Render Suite. So it depends on what you mean by "to their full effect" -- you can use a given MXM file however you wish, but you have no way of editing them, or creating them from scratch.

Just to mention why it works this way, it is not done to purposefully reduce the capability of the plugin. The plugin existed as you are using it (meaning, in conjunction with Maxwell Render Suite) with the demo, before there was ever a standalone version. Any time you are building a plugin for Maxwell, you have some design choices to make regarding materials. You can decide to rely on Maxwell MXED alone, popping that up whenever a person wants to edit a material, or you can try to duplicate the entire MXED user interface inside the plugin. The SketchUp plugin pursued a third way: for use of MXM materials, it would link to files and use MXED to edit them, while offering a unique material editor of its own, which brought some extra value to the system, rather than simply trying to duplicate MXED (not only is that a big job, involving much maintenance, but it essentially adds no new value to the equation). This is what you see in the plugin's "Embedded" material type, which is what you have by default with every material in your SketchUp scene, in the form of the material "Character" and simplified/linked color/texture/bump settings of the Embedded material type. In this model, the plugin essentially augments the limited nature of SketchUp materials with new properties, which remain associated with the native properties of the SketchUp material (color & texture, basically), and with each other (e.g. the bump texture being auto-linked to the color texture, which may or may not be auto-linked to the SketchUp texture), which is something that is not present in the MXM material model.

The question is really whether the Embedded/MXM Modes of the material provide enough flexibility for your purposes, in the absence of Maxwell Render Suite's MXED material editor, and this is a question only you can answer. Also included in the choice must be the fact that Maxwell Studio does offer functionality not present in SketchUp; it is 64-bit, so it can handle any model that can fit in your machine memory, and it has more advanced UV tools than SketchUp does. Furthermore, there are some other benefits to Maxwell Render Suite, which derive from its not being trapped inside of SketchUp, not the least of which is that it allows you to write and render an MXS, while you continue to work in SketchUp. Then, there are other factors, such as the Render Suite's network rendering, and the fact that it comes with all Maxwell plugins, in case you use more than just SketchUp. There are some pages out in the main http://www.maxwellrender.com site which go through and point out some of these considerations.

So, there is some food for thought -- I hope you find it helpful.

[Jonathan B]

That is very helpful and I really appreciate you taking a look at the model when you get a chance.

I do have one query (well several but first and foremost) when you write:

your "high gloss laminate" material is set to use an MXM file. You can end up with a material like this in one of two ways: by using the "Browse for an MXM file" and "Browse the MXM Gallery" buttons in the plugin, or by selecting a material and switching it to use "MXM Mode", by toggling the "MXM" button at the top right of the material editor, and then browsing to an MXM file. What you cannot do is create or edit MXM files -- that requires Maxwell Studio, or the Maxwell MXED material editor, both of which are part of Maxwell Render Suite. So it depends on what you mean by "to their full effect" -- you can use a given MXM file however you wish, but you have no way of editing them, or creating them from scratch.

As you mention, I have set the 'high gloss laminate' to use an MXM file but I think I was able to at least edit the colour of the file 'Guitar body black paint' (from black to white), so I'm a little unclear as to what you mean by this, or whether you are refering to being able to save an edited material? Sketchup does seem to act a little strange when I try this however, and looks like its about to stop working...!

And also when you mention:

The SketchUp plugin pursued a third way: for use of MXM materials, it would link to files and use MXED to edit them, while offering a unique material editor of its own, which brought some extra value to the system, rather than simply trying to duplicate MXED (not only is that a big job, involving much maintenance, but it essentially adds no new value to the equation). This is what you see in the plugin's "Embedded" material type, which is what you have by default with every material in your SketchUp scene, in the form of the material "Character" and simplified/linked color/texture/bump settings of the Embedded material type. In this model, the plugin essentially augments the limited nature of SketchUp materials with new properties, which remain associated with the native properties of the SketchUp material (color & texture, basically), and with each other (e.g. the bump texture being auto-linked to the color texture, which may or may not be auto-linked to the SketchUp texture), which is something that is not present in the MXM material model.

Are you saying that when you use an MXM file, it doesn't use, for example, the bump texture in from the embedded characteristics of the material?

One limitation I was thinking might be quite fundamental was the final render at its upmost resolution in the plugin, but i'm thinking if the render comes out clean enough the images should be good enough to be shown at A2 size without seeming pixelated.

Am I right in thinking that when I render, I should be using 4 threads if my machine is a 64bit? And also i'm assuming for best results I should be using the 'production' mode?

Thanks

[JDHill]

As you mention, I have set the 'high gloss laminate' to use an MXM file but I think I was able to at least edit the colour of the file 'Guitar body black paint' (from black to white), so I'm a little unclear as to what you mean by this, or whether you are refering to being able to save an edited material?

It depends on what you mean (by editing the colour). Linking a material to an MXM is really just taking the file path of the MXM and telling the plugin to hand that to Maxwell when it exports the MXS file for rendering. You can still edit the SketchUp material however you like, but it will have no effect on the scene as rendered. Accordingly, you can edit the MXM file itself, e.g. from black to white, using Maxwell MXED, but this in itself will not change anything about the associated SketchUp material. The takeaway is this: "materials" from the plugin's viewpoint are extra data it has attached to SketchUp materials; at export, for each SketchUp material, either the plugin will generate a material based on the Embedded mode's Character parameters, or it will use the specified MXM file, when the material uses MXM mode.

Sketchup does seem to act a little strange when I try this however, and looks like its about to stop working...!

When you click the "Edit" button in the MXM Mode material, it starts Maxwell MXED, telling it to open the specified MXM file for editing. You need to make your edits, save the material, and close MXED in order to return control to SketchUp. The plugin will then compare the last-write times of the file to see if you have changed it, and re-load its preview image into the plugin material editor.

Are you saying that when you use an MXM file, it doesn't use, for example, the bump texture in from the embedded characteristics of the material?

Exactly, it is an either/or proposition: either the plugin uses the SketchUp material and the Character you've set up for it, or it tells Maxwell to read the specified MXM file and use that.

One limitation I was thinking might be quite fundamental was the final render at its upmost resolution in the plugin, but i'm thinking if the render comes out clean enough the images should be good enough to be shown at A2 size without seeming pixelated.

Yes, the standalone plugin's maximum of HD resolution may pose a significant limitation for serious professional work. Limited resolution is really one of the few artificial limitations -- perhaps the only one, I think. All the other limitations, such as lack of support for render channels (alpha, etc) are inherent to the design of the embedded Maxwell Fire engine that the plugin uses.

Am I right in thinking that when I render, I should be using 4 threads if my machine is a 64bit? And also i'm assuming for best results I should be using the 'production' mode?

The number of threads are not related to the architecture (i.e. 32- or 64-bit) of the machine/OS, and are rather a function of how many CPUs are on the machine, and how many threads per core those CPUs provide. That aside, the answer is that it really depends on what you are doing. While working with the model, you should use the draft engine, with the maximum number of threads that does not bring your machine to a standstill. Setting a threads value of 0 tells the engine to auto-detect the total number of threads available, by the way. Once you are ready to render your final image, you should switch over to the production engine, since while being inferior for realtime work (it takes more sampling levels to get a good idea of the lighting in the scene), it resolves complex lighting scenarios quicker. This is a good time to switch to 0 threads and engage the "Lock" button in the plugin's Maxwell Fire window, to avoid having any inadvertent changes in SketchUp cause a restart of the render.

[Jonathan B]

Thanks, I think I'm getting a better picture now of how the materials work!

And with regard to the 'threads' I'm not sure where I got my information from, but I will follow your description for future rendering. My machine is a (quad core i think) 64-bit i7-2600 @3.40 Ghz Dell Vostro with 8GB Ram. Is this a relatively good spec?

Looking forward to seeing what you may have done to the model, if you have time of course!

Thanks.

[JDHill]

That is a very respectable processor showing good results on the benchwell site; yes, it is a quad core, with two threads per core (for technical details, see here). So the maximum number of rendering threads is eight. 8GB is a decent amount of memory for use with SketchUp, since the theoretical maximum it can use is 4GB (more on the order of 3.2-3.5 in practice), leaving the other 4GB for whatever else you're doing with the machine. Once you get into Maxwell and Maxwell Studio, you can easily use more than that, since 64-bit applications are effectively unrestricted in the amount of memory they can make use of, but of course, we always did okay in the XP days, when the whole OS could use no more than 4GB, with the absolute maximum for a given application being in the 2.5GB range.

I still haven't played with the model, being a bit tied up with trying to finish the rewrite of the plugin UI that has been necessitated by the introduction of SU2013. I'll try to make time for it today, though.

[JDHill]

Okay, I just quickly walked through the scene, noting changes. First, I switched off the BIG EMITTERS layer, as I will not be using those at all. Next, I switched off the RED LIGHTS layer, as I will handle those later. Looking just at the SPOT LIGHTS layer, we see that there are 12 circular faces on this layer, in a single group, which means they all share the output of the 199W @ 12.7 SPOT LIGHTS material. Following is a sequence showing the initial changes.

spotlights only @ 199W, camera EV14:

• 

camera @ EV8:

• 

emitter @ 1200W:

• 

Note that we are seeing reflections from the surfaces where they were lacking with the 80 fake fill lights on BIG EMITTERS enabled. I chose 1200W just estimating that each light should be around 100W. Next, RED LIGHTS is switched back on. Given that the RED LIGHT EMITTERS material is set @ 201W, the relative power outputs seen in this image clearly suggest that more than one mesh is using this material:

• 

Furthermore, hiding both the SPOT LIGHTS and RED LIGHTS layers, just to ensure that there is nothing else using this material, we get no error from the render engine, indicating that there are still emitters assigned somewhere. Here they are, hiding inside the ceiling:

• 

These faces appear to be on the spotlight fixtures. Removing the RED LIGHT EMITTERS material from 10 faces (3 each on the two end fixtures, 2 each on the middle ones), we obtain this error message from the engine when attempting to render:

1. There are no light sources in the scene (emitters, sky, IBL). The render will be black.

Which is exactly what we were looking for, meaning that the only objects now using the RED LIGHT EMITTERS material are the five groups on the RED LIGHTS layer.

This actually provides an excellent partial example of what it means when Maxwell calls itself unbiased. A naive approach would be for the engine to analyze the scene, guess that the camera can't see inside the ceiling, and just discard these extraneous emitter faces. The reason it would be naive is this: it is not actually possible to determine, analytically, whether you can see inside the ceiling or not. On the one hand, the volume may be a closed mesh, where given a material, we should be able to decide, based on the transparency of the material, whether the volume describes a "dead" space. However, this could only be proved in the most trivial of cases, and strictly speaking, not even in those (all textures and parameters would need to be analyzed, with arbitrary limits being chosen to determine whether various interdependent values are close enough to zero to be considered as being zero), given the generic nature of Maxwell's material system -- it does not describe materials in terms of their "transparency"; rather, transparency is something that may or may not result from the combination of components and properties you have used to define the material . And on the other, if the volume is not closed, it is always possible to imagine a more complex array of mirrors by which the camera is able to see inside the volume -- the only method of finding whether this is the case is the rendering process itself, and it does not yield a true/false result; perhaps you just need to render a little longer to finally find that one light path connecting the camera to a light source through a particular series of reflections. None of which is to say that you cannot in many cases make reasonable guesses about such things...but Maxwell doesn't. It does precisely what you tell it to do, and if that means rendering lights inside a ceiling, that is what it will do.

All that aside, it is unlikely that we want 1005W of red light (5 groups @ 201W each), as this is probably supposed to be some sort of strip neon/LED lighting. So, I explode those groups and join them into one, ballparking total emitter power down to 50W @ 26.5 efficacy (based on this random reference, which quotes 26.5 lm/ft where you have about 50ft of lighting) to yield this result:

• 

The reason for exploding/joining here is that the different surfaces differ in area, and would therefore require individual materials to be used, in order to obtain a uniform per-area result. Using Maxwell Studio or MXED to build an MXM, you could approach this by defining the emitter power in terms of lux (lumens per square meter) instead of total watts/efficacy.

I am not going to take it much further than that, just due to time constraints, but I hope you find this helpful. As noted, it's pretty clear, comparing this last image to the one you posted, that what was happening was that those 80 fill lights were simply killing all the highlights in the scene (and also necessitating a camera exposure in which the under-powered spotlights were not even contributing). I will leave it to you to create some other lighting in the scene, if that is appropriate for the setting.

[Jonathan B]

That is such a helpful breakdown of where i have been going astray! Really appreciate your time on this especially given your other commitments.

Just have a couple queries following this, then I hope to be a lot more confident in my next attempts!:

What do you mean by the '@12.7 spot light lights' here?

Looking just at the SPOT LIGHTS layer, we see that there are 12 circular faces on this layer, in a single group, which means they all share the output of the 199W @ 12.7 SPOT LIGHTS material.

I had been messing about with trying to use the sun to render the scene in maxwell and i used the 'hide' tools for the ceiling (from GI). Might that have also influenced the red light spilling through the ceiling given that there were lights hiding up there?

Here they are, hiding inside the ceiling:

Finally, that last render just typifies what I was trying to aim for. All the scene really requires now is some extra general lighting which I can work up more, perhaps by adding a hemispherical emiiter and removing back half as seen here:http://support.nextlimit.com/display/tu ... or+renders. And a play with the materials of the white goalpost, surround to the stage and aluminium trims and skirting.

Thanks again.