thanks thomas and francesco for your comments.
my question about brightness was about not knowing the actual brightness
in the real world, precisely because the monitor can't show you all the
detail. i just wanted to check that that the original .pic image is not
scaled at all by the exposure setting.
thanks again
will
radiance-general-request at radiance-online.org wrote:
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> Today's Topics:
>
> 1. Re: accurate light levels (Thomas Bleicher)
> 2. Re: trad - TclTk (Thomas Bleicher)
> 3. Re: splitting a render by light sources (Thomas Bleicher)
> 4. Re: lightpipes/ports (Francesco Anselmo)
> 5. Re: splitting a render by light sources (Francesco Anselmo)
> 6. Re: lightpipes/ports (Jan Wienold)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 14 Jan 2006 20:06:01 +0100
> From: Thomas Bleicher <tbleicher at arcor.de>
> Subject: Re: [Radiance-general] accurate light levels
> To: Radiance general discussion <radiance-general at radiance-online.org>
> Message-ID: <6098AE5B-9A8E-4198-854E-4C0949E1F3F9 at arcor.de>
> Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
>
>
> On 14.01.2006, at 16:59, william reynolds wrote:
>
> Welcome to Radiance.
>
>
>>hi there
>>
>>As I said in my other question today (spliting a render by light
>>sources)
>>I am quite new to radiance, and I am having some issues setting up my
>>renderings. I have radiance installed and working fine, but I dont
>>quite
>>understand how I make sure the brightness of the final render is
>>realistic.
>>There are a few reasons for this:
>
>
> You don't have to worry much about the "brightness" of images. The
> Radiance
> image file format can store a much greater dynamic range than your
> monitor
> can display or your eyes can see.
>
>
>>I'm not sure what exposure setting to use with pfilt - is it as simple
>>as setting '-e 1' so as not to adjust the exposure? I have tried this
>>and my images all come out very dark, but this might be because I
>>don't
>>have enough light in the scene (see next paragraph, below).
>
>
> The information within the images is not lost until you convert
> the Radiance image (traditionally called *.pic, more resently *.hdr)
> to *.tga (or similar) format which may loose all the details. You can
> convert to some *.tif formats that support the full range but this
> depends on the application you will use to process these images
> afterwards.
>
> And yes, using ra_t16 (for *.tga) or ra_tiff (for *.tif) it is as
> simple as "-e +2" or "-e -2" to make the image brighter or darker.
> Your images may in fact appear dark at the first glance when you render
> a scene designed for 100 sources with one active source only.
>
> Open your rendered image in "ximage" which is designed to handle
> *.pic images. Hit the "a" key or "h" key to perform an adjustment
> of the image exposure on screen, which should give you a better
> rendering (on screen) of the image information. Read the man-page
> of ximage for further details on the controls. Then read the man-page
> of "pcond" which will create an new addjusted image.
>
> Please note that most image manipulation tools bundled with Radiance
> will work as filters and dump their output to your terminal window
> when not told otherwise. Usually you will redirect the output to a
> new file or "pipe" it into another program. These are basic Unix
> concepts you should know to get the most out of your new Linux box.
>
> Examples:
>
> pcond -h+ oldimage.pic > newimage.pic
>
> pcond -h+ oldimage.pic | ra_t16 -3 > newimage.tga
>
>
>>Has anyone used radiance with any theatrical light fixtures?
>>and would they be prepared to share the .rad files for them?
>>I have found the .rad descriptions of architectural fixtures,
>>but i'm not familiar with any of them, and even if I was I need
>>to be able to use accurate models of the specific instruments
>>I'll be using in theatres. I would simply build my own files,
>>using the iestorad utility, but rather unhelpfully the instrument
>>manufacturers dont seem willing to give out ies data.
>
>
> Rob Shakespeare, coauthor of "Rendering with Radiance" (see below)
> has experiance in this field, as have some others here on the list.
>
> IIRC there was a post a few weeks ago about theatrical lights.
> I'm not shure if the poster was willing to share his homemade
> messurments of some fixtures. Hope he will answer personally.
>
>
>>Has anyone made any more materials information available to the
>>public? I have looked through the material.rad list of materilas
>>in the lib folder, but I'm specifically looking black paint and
>>heavy black cloth type materials. If not, then does anyone have
>>any recomendations of how to go about determining good values to
>>use in my own materials definitions? I dont have access to any
>>way of measuring reflected light levels in an experiment.
>
>
> You can find a short introduction to the radiance materials
> at other things here:
>
> http://radsite.lbl.gov/radiance/refer/usman1.pdf
>
> and here (follow link "Documentation" and start with the
> "radcourse_basic.pdf" document)
>
> http://luminance.londonmet.ac.uk/learnix/
>
> While browsing for the link to Axel Jacobs more resent tutorials
> I found this overview of materials:
>
> http://www.learn.londonmet.ac.uk/student/resources/radiance/
> material_db.shtml
>
> Everyone highly recommends "The Book" about Radiance:
>
> http://radsite.lbl.gov/radiance/book/
>
> It even includes a chapter about "Dramatic Lighting" (stage lighting).
>
>
>>Thanks for your help with my probably rather basic questions
>>Will
>
>
>
> Everyone has his/her share of problems with Radiance ;)
>
> Thomas
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Sat, 14 Jan 2006 20:27:10 +0100
> From: Thomas Bleicher <tbleicher at arcor.de>
> Subject: Re: [Radiance-general] trad - TclTk
> To: Radiance general discussion <radiance-general at radiance-online.org>
> Message-ID: <29826132-3949-44C5-A91F-6FEDB66FEC6E at arcor.de>
> Content-Type: text/plain; charset=US-ASCII; format=flowed
>
>
> On 14.01.2006, at 17:08, william reynolds wrote:
>
>
>>From looking over the past posts it seems that something has been
>>changed in the Tcl/Tk language that means that the trad utility
>>will no longer run with more recent versions. Does anyone know
>>with which version of Tcl/Tk this issue frst raised its head?
>>I've only tried the most recent versions. I also tried to install
>>the version I believe trad is meant to run under (Tcl 7.4, Tk 4)
>>but the source for these no longer under the new gcc!
>
>
> Don't waste your preciouse time with old dead scripts. (Or do
> it right and update the code for current releases if you know
> enough about TCL/TK).
>
>
>>I'm pretty new to the linux system im running (fresh from windows)
>>and I dont really know what I'm doing changing code, so I thought
>>I'd appeal to this list for advice about any other front-ends for
>>Radiance.
>
>
> You don't need much of a front end for Radiance except if you're
> afraid of the command line. Most documentation you will find on
> the LNBL homepage will use tipped out commands and a text editor
> to create the scene files.
>
> You can try the Radiance_on_a_Disk LEARNIX distribution by
> Axel Jacobs:
>
> http://luminance.londonmet.ac.uk/learnix/
>
> The documentation (including the "radcourse" PDFs I mentioned in
> my other post) should match this environment so you don't have
> to wrestle with the installation to get examples running.
>
> A usefull front-end for the Radiance bundle of tools is the
> programm "rad" which will controll the creation of octrees etc.
> for you. It's included in the Radiance distribution. Read the
> man-page about how to use it.
>
> And start learning bash.
>
>
>>I'm aware of Rayfront, but unfortunately I dont have much budget
>>to spend on this project (it's my 4th year undergraduateEngineering
>>degree final project) and I am hoping for a free version!
>
>
> Rayfront is one of the best front ends I know about. Perhaps
> you can convince your department to invest in an educational licence?
> Would be good for the development of Rayfront, too.
>
> Thomas
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Sat, 14 Jan 2006 20:55:57 +0100
> From: Thomas Bleicher <tbleicher at arcor.de>
> Subject: Re: [Radiance-general] splitting a render by light sources
> To: Radiance general discussion <radiance-general at radiance-online.org>
> Message-ID: <BBC4483E-2FB5-40BB-B27C-8B6C17B32159 at arcor.de>
> Content-Type: text/plain; charset=US-ASCII; format=flowed
>
>
> On 14.01.2006, at 16:23, william reynolds wrote:
>
>
>>hi there
>>i'm fairly new to the radiance package, and to rendering in
>>general, but i have a fairly specific project on the go, with
>>which i need some help.
>>
>>i am trying to use radiance to render a relatively simple model
>>geometrically - just a simple room, with a box sitting on the
>>floor - but with up to 100 or so light sources. but the difference
>>is that i want to get a separte image file for each light
>>source - i.e. hundred or so images, with only 1 light on in each.
>>i will then use superposition and recombine the images later,
>>allowing me to vary the intensities of each light source.
>
>
> I hope you are aware of the fact that a incandescent light source
> will have a shift of the spectrum in it's output when you change
> the intensity (reduce the power for the lamp). But I don't think
> you're bothered about this (small) aspect, so let's move on.
>
>
>>is there any kind of built in functionality in radiance to
>>allow me to do this, or do i have to write a shell script or
>>something (and if so, can anyone point me towards a good place
>>to learn how! i come from a very winndows based background)
>
>
> The "build in functionality" of Radiance is it's simplicity.
> Small tools for small tasks. And yes, you will have to write
> a script for your problem. But it will be a simple script.
>
> First you have to organize your scene data:
>
> a) everything that is static in the scene in one file
> b) a bunch of files containing everything that isn't
> (in your case 100 files with the description of 1 light
> source each).
> c) definitions of i.e. viewpoints or render parameters
>
> The basic steps to create one image are:
>
> 1) Compile a scene octree from the static and one dynamic file
> 2) Render the image with the created octree as input
>
> I don't know much about your light so I assume you have
> created a "static.rad" file, 100 "dynamic.001" etc. files
> and a file with render options "render.opt".
>
> Creating your images is as simple as:
>
> for i in `seq -w 100`
> do
> oconv static.rad dynamic.${i} > tmp_scene.oct
> rpict @render.opt tmp_scene.oct > image_${i}.pic
> done
>
> Not as bad as it sounds, eh?
>
> There is plenty of room for improvements: in particular, you don't
> need all the 100 files for light sources if the vary only in
> position or in other small details. That could be done within
> the "for ..." loop, too. All depends on your needs.
>
>
> For a simple introduction to bash google for "bash tutorial"
> and try a few of the hits. It depends on you what's the right
> introduction level. You can use any other scripting language
> as well (Python, Perl, TCL) if you already know one.
>
>
> HTH,
> Thomas
>
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Sat, 14 Jan 2006 22:32:15 +0000
> From: Francesco Anselmo <pisuke at blueyonder.co.uk>
> Subject: Re: [Radiance-general] lightpipes/ports
> To: Radiance general discussion <radiance-general at radiance-online.org>
> Message-ID: <200601142232.15784.pisuke at blueyonder.co.uk>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Erico
>
>>Thanks for the pointer. I've downloaded the pmap 4.3 version and tried
>>to compile/install (after performing a fresh installation of radiance
>>3.7), but the pmap installation is unsuccessful.
>
>
> If you're using linux, you can download the new pmap binaries from this page:
> http://www.bozzograo.net/radiance/modules.php?op=modload&name=Downloads&file=index&req=viewdownload&cid=4
>