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Testing for 'Bad Cholesterol' Doesn't Tell the Whole Story
Testing for'Bad Cholesterol' Doesn't Tell the Whole Story So why don't more doctors use it? For decades, assessing cholesterol risk has been built around a simple idea: Lower "bad" cholesterol, lower your chance of a heart attack . The test at the center of that approach measures how much low-density lipoprotein, or LDL cholesterol, is circulating in part of the blood. It has shaped everything from clinical guidelines to the widespread use of statins, medications that reduce LDL. Lowering LDL cholesterol reduces heart attacks, strokes, and early death.
Appendix
The introduction of convolution and attention to the space of rays in 3D required additional geometric representations for which there was no space in the main paper to elaborate. We will introduce here all the necessary notations and definitions. We have accompanied this presentation with examples of specific groups to elucidate the abstract concepts needed in the definitions. Figure 10: The visualization of Plücker coordinates: A ray xcan be denoted as (d,m)where x is any point on the ray x, and dis the direction of the ray x. mis defined as x d. Given the action of the group G on a homogeneous space X, and given x0 as the origin of X, the stabilizer group H of x0 in G is the group that leaves x0 intact, i.e., H = {h G|hx0 = x0}. The group, G, can be partitioned into the quotient space (the set of left cosets) G/H and X is isomorphic to G/H since all group elements in the same coset transform x0 to the same element in X, that is, for any element g gH we have g x0 = gx0. Example 1. SE(3) acting on the ray space R: Take SE(3) as the acting group and the ray space R as its homogeneous space. We use Plücker coordinates to parameterize the ray space R: any x R can be denoted as (d,m), where d S2 is the direction of the ray, and m = x d where x is any point on the ray, as shown in figure 10. R is the quotient space SE(3)/(SO(2) R)up to isomorphism. Example 2. SE(3) acting on the 3DEuclidean space R3: R3 is isomorphic to SE(3)/SO(3). Consider another case when SE(3) acts on the homogeneous space R3; for any g = (R,t) SE(3) and x R3, gx = Rx+t. If the fixed origin is [0,0,0]T, the stabilizer subgroup is H = SO(3) since any rotation g = (R,0)leaves [0,0,0]T unchanged. The last example is SO(3) acting on the homogeneous space sphere S2. Given the fixed origin point as [0,0,1]T, the stabilizer group is SO(2).
Rad-NeRF: Ray-decoupled Training of Neural Radiance Field
Although the neural radiance field (NeRF) exhibits high-fidelity visualization on the rendering task, it still suffers from rendering defects, especially in complex scenes. In this paper, we delve into the reason for the unsatisfactory performance and conjecture that it comes from interference in the training process. Due to occlusions in complex scenes, a 3D point may be invisible to some rays. On such a point, training with those rays that do not contain valid information about the point might interfere with the NeRF training. Based on the above intuition, we decouple the training process of NeRF in the ray dimension softly and propose a Ray-decoupled Training Framework for neural rendering (Rad-NeRF). Specifically, we construct an ensemble of sub-NeRFs and train a soft gate module to assign the gating scores to these sub-NeRFs based on specific rays.
Reducing Shape-Radiance Ambiguity in Radiance Fields with a Closed-Form Color Estimation Method Qihang Fang 1,2,* Y afei Song 3,* Keqiang Li
A neural radiance field (NeRF) enables the synthesis of cutting-edge realistic novel view images of a 3D scene. It includes density and color fields to model the shape and radiance of a scene, respectively. Supervised by the photometric loss in an end-to-end training manner, NeRF inherently suffers from the shape-radiance ambiguity problem, i.e., it can perfectly fit training views but does not guarantee decoupling the two fields correctly.