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--- 02_user_tutorials:04_light_modelling:use_fluxmodel [2025/01/24 15:51] – removed - external edit (Unknown date) 127.0.0.1
+++ 02_user_tutorials:04_light_modelling:use_fluxmodel [2025/01/24 15:51] (current) – ↷ Page moved from 02_user_tutorials:light_modelling:use_fluxmodel to 02_user_tutorials:04_light_modelling:use_fluxmodel tim2
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+In this tutorial we will see how to get started with a FluxModel in GroIMP.
+Go [[01_user_documentation:groimp-platform:gpuflux|here]] to see more about how the FluxModel is defined in GroIMP.
+====== Light Model ======
+First, we setup of the Flux Light Model:
+<code java>
+import de.grogra.gpuflux.tracer.FluxLightModelTracer.MeasureMode;
+import de.grogra.gpuflux.scene.experiment.Measurement;
+const int RAYS = 10000000;
+const int DEPTH = 10;
+const FluxLightModel LM = new FluxLightModel(RAYS,
+DEPTH);
+protected void init () {
+LM.setMeasureMode(MeasureMode.FULL_SPECTRUM);
+LM.setSpectralBuckets(81);
+LM.setSpectralDomain(380, 780);
+}
+</code>
+This is:
+  - importing of the needed classes
+  - initializing the model with 10 million rays and a recursion depth of 10
+  - setting the parameters with 400nm divided into 80 buckets of 5nm.
+Then, run the light model and determine the amount of sensed radiation or of
+absorbed power for an object-type.
+<code java>
+public void run () [
+{
+LM.compute();
+}
+x:SensorNode ::> {
+Measurement spectrum = LM.getSensedIrradianceMeasurement(x);
+float absorbedPower = spectrum.integrate();
+//...
+}
+x:Box ::> {
+Measurement spectrum = LM.getAbsorbedPowerMeasurement(x);
+float absorbedPower = spectrum.integrate();
+//...
+}
+]
+</code>
+This is:
+  - computing the model
+  - computing the integration of the whole absorbed spectrum for both
+  - sensor nodes
+  - box objects
+Demonstration of the method for the determination of the amount of absorbed power per bucket or integration over a certain spectral range.
+<code java>
+Measurement spectrum = LM.getAbsorbedPowerMeasurement(x);
+//absorbed power for the first bucket: 380-385 nm
+float ap380_385 = spectrum.data[0];
+//accumulate absorbed power for the first four 50 nm buckets
+float b0 = 0, b1 = 0, b2 = 0, b3 = 0;
+for (int i:(0:10)) {
+b0 += spectrum.data[i];
+b1 += spectrum.data[i + 10];
+b2 += spectrum.data[i + 20];
+b3 += spectrum.data[i + 30];
+}
+//integrate the whole spectrum
+float ap = spectrum.integrate();
+</code>
+This is:
+  - Getting the absorbed spectrum
+  - Storing the first bucket in a variable
+  - building four integrals, each of 50 nm (10 buckets of 5 nm) and sum up the first 40 buckets.
+  - calculating the integral over the whole spectrum.
+====== Light Sources ======
+Now let's set up a parameterisable light node – with explicit definition of physical light and spectral power distribution by simple arrays:
+<code java>
+import de.grogra.imp3d.spectral.IrregularSpectralCurve;
+const double[][] DISTRIBUTION = {
+{131.25, 131.67, 132.37, ...},
+{131.36, 131.81, ...},
+...
+};
+static const float[] WAVELENGTHS = {380,385, ...};
+static const float[] AMPLITUDES = {0.000967,0.000980, ...};
+module MyLamp extends LightNode() {
+{
+setLight(new SpectralLight(
+new IrregularSpectralCurve(WAVELENGTHS, AMPLITUDES)).(
+setPower(10), //[W]
+setLight(new PhysicalLight(DISTRIBUTION))));
+}
+}
+</code>
+This is :
+  - importing the required classes
+  - defining of the physical light distribution
+  - defining of the spectral power distribution
+  - defining of a lamp using the specified parameters
+The light distribution and spectral distribution (i.e. the ''DISTRIBUTION'', ''WAVELENGTHS'' and ''AMPLITUDES'' arrays) can also be provided from ''.ies'' files.
+See [[01_user_documentation:groimp-platform:input-and-output-in-groimp|here]] for more information on the supported file formats.
+Then, let's create a parameterizable light node – using file references for physical and spectral power distribution.
+<code java>
+const LightDistributionRef DISTRIBUTION = light("
+distribution1");
+const SpectrumRef SPECTRUM = spectrum("equal");
+module MyLamp1 extends LightNode {
+{
+setLight(new SpectralLight(new PhysicalLight(
+DISTRIBUTION), SPECTRUM, 10)); // 10 W
+}
+}
+module MyLamp2 extends LightNode {
+{
+setLight(
+new SpectralLight().(
+setPower(10), //[W]
+setLight(new PhysicalLight(DISTRIBUTION)),
+setSpectrum(SPECTRUM)));
+}
+}
+</code>
+This is:
+  - Defining a file reference. This file can be included or linked to a project
+  - Applying a concrete lamp to the reference by:
+    - using the constructor
+    - using the set-methods of the //LightNode// class
+====== Illumination Model ======
+Definition of a Phong shader by textures, by colours and by a user-defined
+spectral power distribution.
+<code java>
+Phong myShader = new Phong();
+ImageMap image = new ImageMap();
+image.setImageAdapter(new FixedImageAdapter(image("leaf").toImageAdapter().getBufferedImage()));
+myShader.setDiffuse(image);
+Phong myShader = new Phong();
+myShader.setDiffuse(new RGBColor(0,1,0));
+//myShader.setSpecular(new Graytone(0.5));
+//myShader.setShininess(new Graytone(0.5));
+myShader.setDiffuseTransparency(new RGBColor(0.5,0,0));
+//myShader.setAmbient(new Graytone(0.5));
+//myShader.setEmissive(new Graytone(0.5));
+ChannelSPD MySPD = new ChannelSPD(new IrregularSpectralCurve(
+    new float[] {400,410, ....,740,750}, //WAVELENGTHS
+    new float[] {0.1,0, .... ,0.4,0.25} //AMPLITUDES
+));
+Phong myShader = new Phong();
+myShader.setDiffuse(MySPD);
+</code>
+This is:
+  - Setting an image as texture: Values for reflection depend on the colour of the texture at each pixel of the image.
+  - Setting specific properties: At this configuration green will be reflected to 100 % and red will be transmitted to 50 % for the whole surface of the object.
+  - A user-defined SPD is used to define the diffuse colour.