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18-Jan-2022   
Path: RAMI-IV : EXPERIMENTS : ACTUAL CANOPIES : OFENPASS WINTER PINESTAND : BRF in azimuth ring (total)
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BRF in azimuthal ring (total): brfazim

Within RAMI the Bi-directional Reflectance Factor (BRF) at a specific wavelength is defined as the radiant flux exiting from a target area in a particular direction - passing through a (virtual) planar reference surface of specified lateral dimension and elevation above the target, and oriented perpendicular to the underlying surface normal - normalized by the equivalent quantity leaving from an infinitely large Lambertian background via the same reference surface and for the same directions of illumination and reflectance. Alternatively, the BRF of this reference surface can be said to be:

where the BRDF can be expressed in terms of the incident (i) and reflected (r) radiance L [W ⋅ m−2 ⋅ sr−1]:

brfazim requires measurements carried out for a view zenith angle of 37 degree at 2 degree intervals of the relative azimuth angle (defined as the absolute value of the difference between illumination azimuth and view azimuth angles) covering the range from 0 (viewer has same azimuth as illumination source) to 358 degree (i.e., 180 measurements). Although singular directions are preferred, it is left to the RAMI participants to choose the solid angle over which to integrate the exiting radiation, as long as they are centered at the above relative azimuth angles. The height of the reference surface is that of the top of the simulated scene and covers the entire extend of that scene - unless specified otherwise in the experiment description page.

Within RAMI-IV this measurement applies only to a selection of canopy scenes:

    Formatting of measurement-file content:

    Header line content # rows # columns in file Ratio of filtered rays **
    Header line format integer integer real
    Body lines content SZA [rad] VZA [rad] | SAA - VAA | [rad] BRF Std. Dev. BRF **
    Body lines format real real real real real
    **: if available, otherwise set to −1.000000.

    where

    • SZA: Solar Zenith Angle
    • SAA: Solar Azimuth Angle
    • VZA: Viewing Zenith Angle
    • VAA: Viewing Azimuth Angle
    • Ratio of filtered rays: The number of rays that perform the measurement divided by the total number of incident rays (for ray-tracing RT models only).
    • Std. Dev. BRF: Indication of the uncertainty in the BRF estimate as estimated from the radiative transfer model itself
    • A real is defined as having 6 digits after the decimal point, e.g., 1.000000.

    Example output:

              180           5      1.000000
    0.349066	0.645772	0.000000	0.073226	-1.000000
    0.349066	0.645772	0.034907	0.072851	-1.000000	
    0.349066	0.645772	0.069813	0.072385	-1.000000	
    0.349066	0.645772	0.104720	0.071834	-1.000000	
    0.349066	0.645772	0.139626	0.071308	-1.000000	
    0.349066	0.645772	0.174533	0.070851	-1.000000	
    0.349066	0.645772	0.209440	0.070273	-1.000000	
    0.349066	0.645772	0.244346	0.069722	-1.000000	
    0.349066	0.645772	0.279253	0.069247	-1.000000	
    0.349066	0.645772	0.314159	0.068704	-1.000000	
    0.349066	0.645772	0.349066	0.068192	-1.000000	
    0.349066	0.645772	0.383972	0.067659	-1.000000	
    0.349066	0.645772	0.418879	0.067121	-1.000000	
    0.349066	0.645772	0.453786	0.066662	-1.000000	
    0.349066	0.645772	0.488692	0.066183	-1.000000	
    0.349066	0.645772	0.523599	0.065705	-1.000000	
    0.349066	0.645772	0.558505	0.065206	-1.000000	
    0.349066	0.645772	0.593412	0.064798	-1.000000	
    0.349066	0.645772	0.628319	0.064472	-1.000000	
    0.349066	0.645772	0.663225	0.064103	-1.000000	
    0.349066	0.645772	0.698132	0.063693	-1.000000	
    0.349066	0.645772	0.733038	0.063517	-1.000000	
    0.349066	0.645772	0.767945	0.063265	-1.000000	
    0.349066	0.645772	0.802851	0.063057	-1.000000	
    0.349066	0.645772	0.837758	0.063005	-1.000000	
    0.349066	0.645772	0.872665	0.062812	-1.000000	
    0.349066	0.645772	0.907571	0.062614	-1.000000	
    0.349066	0.645772	0.942478	0.062381	-1.000000	
    0.349066	0.645772	0.977384	0.062217	-1.000000	
    0.349066	0.645772	1.012291	0.062000	-1.000000	
    0.349066	0.645772	1.047198	0.061759	-1.000000	
    0.349066	0.645772	1.082104	0.061532	-1.000000	
    0.349066	0.645772	1.117011	0.061280	-1.000000	
    0.349066	0.645772	1.151917	0.060911	-1.000000	
    0.349066	0.645772	1.186824	0.060722	-1.000000	
    0.349066	0.645772	1.221730	0.060440	-1.000000	
    0.349066	0.645772	1.256637	0.060283	-1.000000	
    0.349066	0.645772	1.291544	0.059973	-1.000000	
    0.349066	0.645772	1.326450	0.059753	-1.000000	
    0.349066	0.645772	1.361357	0.059569	-1.000000	
    0.349066	0.645772	1.396263	0.059305	-1.000000	
    0.349066	0.645772	1.431170	0.058944	-1.000000	
    0.349066	0.645772	1.466077	0.058719	-1.000000	
    0.349066	0.645772	1.500983	0.058446	-1.000000	
    0.349066	0.645772	1.535890	0.058157	-1.000000	
    0.349066	0.645772	1.570796	0.057889	-1.000000	
    0.349066	0.645772	1.605703	0.057635	-1.000000	
    0.349066	0.645772	1.640609	0.057461	-1.000000	
    0.349066	0.645772	1.675516	0.057251	-1.000000	
    0.349066	0.645772	1.710423	0.057270	-1.000000	
    0.349066	0.645772	1.745329	0.057306	-1.000000	
    0.349066	0.645772	1.780236	0.057114	-1.000000	
    0.349066	0.645772	1.815142	0.057245	-1.000000	
    0.349066	0.645772	1.850049	0.057207	-1.000000	
    0.349066	0.645772	1.884956	0.057278	-1.000000	
    0.349066	0.645772	1.919862	0.057263	-1.000000	
    0.349066	0.645772	1.954769	0.057068	-1.000000	
    0.349066	0.645772	1.989675	0.057066	-1.000000	
    0.349066	0.645772	2.024582	0.057018	-1.000000	
    0.349066	0.645772	2.059489	0.057084	-1.000000	
    0.349066	0.645772	2.094395	0.057197	-1.000000	
    0.349066	0.645772	2.129302	0.057241	-1.000000	
    0.349066	0.645772	2.164208	0.057208	-1.000000	
    0.349066	0.645772	2.199115	0.057222	-1.000000	
    0.349066	0.645772	2.234021	0.056993	-1.000000	
    0.349066	0.645772	2.268928	0.056799	-1.000000	
    0.349066	0.645772	2.303835	0.056740	-1.000000	
    0.349066	0.645772	2.338741	0.056715	-1.000000	
    0.349066	0.645772	2.373648	0.056734	-1.000000	
    0.349066	0.645772	2.408554	0.056986	-1.000000	
    0.349066	0.645772	2.443461	0.057104	-1.000000	
    0.349066	0.645772	2.478368	0.057153	-1.000000	
    0.349066	0.645772	2.513274	0.057184	-1.000000	
    0.349066	0.645772	2.548181	0.057279	-1.000000	
    0.349066	0.645772	2.583087	0.057428	-1.000000	
    0.349066	0.645772	2.617994	0.057536	-1.000000	
    0.349066	0.645772	2.652900	0.057793	-1.000000	
    0.349066	0.645772	2.687807	0.057882	-1.000000	
    0.349066	0.645772	2.722714	0.057976	-1.000000	
    0.349066	0.645772	2.757620	0.058210	-1.000000	
    0.349066	0.645772	2.792527	0.058414	-1.000000	
    0.349066	0.645772	2.827433	0.058745	-1.000000	
    0.349066	0.645772	2.862340	0.058966	-1.000000	
    0.349066	0.645772	2.897247	0.059244	-1.000000	
    0.349066	0.645772	2.932153	0.059465	-1.000000	
    0.349066	0.645772	2.967060	0.059655	-1.000000	
    0.349066	0.645772	3.001966	0.059881	-1.000000	
    0.349066	0.645772	3.036873	0.060156	-1.000000	
    0.349066	0.645772	3.071779	0.060433	-1.000000	
    0.349066	0.645772	3.106686	0.060679	-1.000000	
    0.349066	0.645772	3.141593	0.060850	-1.000000	
    0.349066	0.645772	3.176499	0.061147	-1.000000	
    0.349066	0.645772	3.211406	0.061431	-1.000000	
    0.349066	0.645772	3.246312	0.061577	-1.000000	
    0.349066	0.645772	3.281219	0.061902	-1.000000	
    0.349066	0.645772	3.316126	0.062195	-1.000000	
    0.349066	0.645772	3.351032	0.062697	-1.000000	
    0.349066	0.645772	3.385939	0.063044	-1.000000	
    0.349066	0.645772	3.420845	0.063522	-1.000000	
    0.349066	0.645772	3.455752	0.063887	-1.000000	
    0.349066	0.645772	3.490659	0.064451	-1.000000	
    0.349066	0.645772	3.525565	0.064874	-1.000000	
    0.349066	0.645772	3.560472	0.065444	-1.000000	
    0.349066	0.645772	3.595378	0.066070	-1.000000	
    0.349066	0.645772	3.630285	0.066604	-1.000000	
    0.349066	0.645772	3.665191	0.067138	-1.000000	
    0.349066	0.645772	3.700098	0.067658	-1.000000	
    0.349066	0.645772	3.735005	0.068192	-1.000000	
    0.349066	0.645772	3.769911	0.068793	-1.000000	
    0.349066	0.645772	3.804818	0.069243	-1.000000	
    0.349066	0.645772	3.839724	0.069786	-1.000000	
    0.349066	0.645772	3.874631	0.070335	-1.000000	
    0.349066	0.645772	3.909538	0.070850	-1.000000	
    0.349066	0.645772	3.944444	0.071523	-1.000000	
    0.349066	0.645772	3.979351	0.072111	-1.000000	
    0.349066	0.645772	4.014257	0.072829	-1.000000	
    0.349066	0.645772	4.049164	0.073476	-1.000000	
    0.349066	0.645772	4.084070	0.074057	-1.000000	
    0.349066	0.645772	4.118977	0.074710	-1.000000	
    0.349066	0.645772	4.153884	0.075376	-1.000000	
    0.349066	0.645772	4.188790	0.076051	-1.000000	
    0.349066	0.645772	4.223697	0.076704	-1.000000	
    0.349066	0.645772	4.258603	0.077312	-1.000000	
    0.349066	0.645772	4.293510	0.077986	-1.000000	
    0.349066	0.645772	4.328417	0.078638	-1.000000	
    0.349066	0.645772	4.363323	0.079353	-1.000000	
    0.349066	0.645772	4.398230	0.080053	-1.000000	
    0.349066	0.645772	4.433136	0.080689	-1.000000	
    0.349066	0.645772	4.468043	0.081540	-1.000000	
    0.349066	0.645772	4.502949	0.082241	-1.000000	
    0.349066	0.645772	4.537856	0.082929	-1.000000	
    0.349066	0.645772	4.572763	0.083783	-1.000000	
    0.349066	0.645772	4.607669	0.084569	-1.000000	
    0.349066	0.645772	4.642576	0.085353	-1.000000	
    0.349066	0.645772	4.677482	0.086137	-1.000000	
    0.349066	0.645772	4.712389	0.086841	-1.000000	
    0.349066	0.645772	4.747296	0.087675	-1.000000	
    0.349066	0.645772	4.782202	0.088510	-1.000000	
    0.349066	0.645772	4.817109	0.089394	-1.000000	
    0.349066	0.645772	4.852015	0.090438	-1.000000	
    0.349066	0.645772	4.886922	0.091657	-1.000000	
    0.349066	0.645772	4.921828	0.093202	-1.000000	
    0.349066	0.645772	4.956735	0.095006	-1.000000	
    0.349066	0.645772	4.991642	0.097435	-1.000000	
    0.349066	0.645772	5.026548	0.100564	-1.000000	
    0.349066	0.645772	5.061455	0.104542	-1.000000	
    0.349066	0.645772	5.096361	0.109471	-1.000000	
    0.349066	0.645772	5.131268	0.115825	-1.000000	
    0.349066	0.645772	5.166175	0.123968	-1.000000	
    0.349066	0.645772	5.201081	0.136423	-1.000000	
    0.349066	0.645772	5.235988	0.137422	-1.000000	
    0.349066	0.645772	5.270894	0.124394	-1.000000	
    0.349066	0.645772	5.305801	0.116125	-1.000000	
    0.349066	0.645772	5.340708	0.109739	-1.000000	
    0.349066	0.645772	5.375614	0.104668	-1.000000	
    0.349066	0.645772	5.410521	0.100764	-1.000000	
    0.349066	0.645772	5.445427	0.097679	-1.000000	
    0.349066	0.645772	5.480334	0.095329	-1.000000	
    0.349066	0.645772	5.515240	0.093454	-1.000000	
    0.349066	0.645772	5.550147	0.092049	-1.000000	
    0.349066	0.645772	5.585054	0.090762	-1.000000	
    0.349066	0.645772	5.619960	0.089613	-1.000000	
    0.349066	0.645772	5.654867	0.088612	-1.000000	
    0.349066	0.645772	5.689773	0.087776	-1.000000	
    0.349066	0.645772	5.724680	0.086889	-1.000000	
    0.349066	0.645772	5.759587	0.085989	-1.000000	
    0.349066	0.645772	5.794493	0.085165	-1.000000	
    0.349066	0.645772	5.829400	0.084224	-1.000000	
    0.349066	0.645772	5.864306	0.083326	-1.000000	
    0.349066	0.645772	5.899213	0.082523	-1.000000	
    0.349066	0.645772	5.934119	0.081575	-1.000000	
    0.349066	0.645772	5.969026	0.080696	-1.000000	
    0.349066	0.645772	6.003933	0.079743	-1.000000	
    0.349066	0.645772	6.038839	0.078798	-1.000000	
    0.349066	0.645772	6.073746	0.077992	-1.000000	
    0.349066	0.645772	6.108652	0.077132	-1.000000	
    0.349066	0.645772	6.143559	0.076385	-1.000000	
    0.349066	0.645772	6.178466	0.075465	-1.000000	
    0.349066	0.645772	6.213372	0.074758	-1.000000	
    0.349066	0.645772	6.248279	0.074064	-1.000000	
    

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