Fact-checked by Grok 2 weeks ago

Vector area

The vector area, also known as the area vector, is a vector quantity in mathematics and physics that characterizes a surface by combining its scalar area (magnitude) with a direction perpendicular to the surface, where the direction is conventionally defined using the right-hand rule relative to the surface's boundary or orientation.^[1] This concept extends the idea of signed area from two dimensions to three, enabling the treatment of surfaces as oriented entities in vector calculus.^[2] For a planar surface spanned by two vectors \vec{u} and \vec{v}, the vector area \vec{A} is given by the cross product \vec{A} = \vec{u} \times \vec{v}, whose magnitude equals the area of the parallelogram formed by \vec{u} and \vec{v}, and direction is normal to the plane.^[3] More generally, for a polygonal surface, \vec{A} is the sum of such cross products over adjacent position vectors from a common point, or equivalently \vec{A} = \frac{1}{2} \oint \vec{r} \times d\vec{l} along the boundary curve, where \vec{r} is the position vector.^[4] For non-planar or curved surfaces, the total vector area is the integral \vec{A} = \int_S d\vec{A}, with the infinitesimal element d\vec{A} pointing outward or according to a chosen convention, and its magnitude dA being the local scalar area. A key property is that the vector area of any closed surface (with no boundary) integrates to zero, as inward and outward contributions cancel.^[4] In physics, vector area plays a crucial role in formulating laws involving surfaces and fields. In electrostatics, it defines electric flux as \Phi_E = \int_S \vec{E} \cdot d\vec{A}, which underpins Gauss's law relating flux to enclosed charge.^[4] In magnetostatics, the magnetic flux through a surface is \Phi_B = \int_S \vec{B} \cdot d\vec{A}, and for a planar current loop, the magnetic dipole moment is \vec{m} = I \vec{A}, where I is the current; this moment determines the loop's interaction with external fields, such as torque \vec{\tau} = \vec{m} \times \vec{B}.^[5] Beyond electromagnetism, vector area appears in fluid mechanics for momentum flux across surfaces and in rigid body dynamics for angular momentum calculations involving projected areas.^[6] These applications highlight its utility in simplifying integrals over oriented surfaces, making it indispensable for theorems like Stokes' and the divergence theorem in vector analysis.^[7]

Mathematical Foundations

Definition for Planar Surfaces

The vector area \mathbf{A} of a planar region is defined as a vector perpendicular to the plane containing the region, with magnitude equal to the scalar area A of the region and direction determined by the right-hand rule applied to the orientation of the region's boundary.^[8] This direction corresponds to a unit normal vector \hat{n} pointing outward from the boundary when the fingers of the right hand curl in the direction of the boundary traversal, yielding the expression \mathbf{A} = A \hat{n}.^[8] The magnitude A has units of area, such as square meters in the SI system.^[8] For a simple polygon lying in a plane, the vector area admits a formal boundary integral expression \mathbf{A} = \frac{1}{2} \oint_{\partial S} \mathbf{r} \times d\mathbf{l}, where the closed integral is taken over the oriented boundary curve \partial S, \mathbf{r} is the position vector of a point on the boundary relative to an arbitrary origin, and d\mathbf{l} is the infinitesimal directed line element along the boundary.^[9] As a specific case, consider a triangle in the plane with vertices at position vectors \mathbf{r}_1, \mathbf{r}_2, and \mathbf{r}_3, oriented counterclockwise when viewed from the side where \hat{n} points outward. The vector area is then \mathbf{A} = \frac{1}{2} (\mathbf{r}_2 - \mathbf{r}_1) \times (\mathbf{r}_3 - \mathbf{r}_1), which follows from applying the cross product to two sides of the triangle emanating from \mathbf{r}_1 and dividing by 2 to account for the triangular geometry.^[10] This expression preserves the perpendicular direction via the cross product and the right-hand rule for the chosen vertex ordering.^[10]

Generalization to Curved Surfaces

The vector area of a curved surface is defined as the surface integral of the infinitesimal area vectors over the surface, capturing both magnitude and orientation. For a surface parametrized by position vector \mathbf{r}(u,v) over parameter domain D, the vector area is \mathbf{A} = \iint_D (\mathbf{r}_u \times \mathbf{r}_v) \, du \, dv, where \mathbf{r}_u = \partial \mathbf{r}/\partial u and \mathbf{r}_v = \partial \mathbf{r}/\partial v provide the tangent vectors whose cross product gives the oriented area element.^[11] This formulation extends the planar case, where the vector area is simply the scalar area times a constant normal, but for curved surfaces it accounts for varying local orientations through the direction of each \mathbf{r}_u \times \mathbf{r}_v. In contrast to the scalar surface area \iint_D \|\mathbf{r}_u \times \mathbf{r}_v\| \, du \, dv, which sums magnitudes without regard to direction, the vector area is a vector sum that can exhibit partial cancellations due to opposing orientations on different parts of the surface, potentially resulting in a net direction that deviates from a simple average of local normals for asymmetric or highly curved geometries.^[11] A representative example is the upper hemisphere of radius R centered at the origin, parametrized in spherical coordinates with \theta \in [0, \pi/2] and \phi \in [0, 2\pi]. The net vector area points along the positive z-axis by symmetry, with magnitude \pi R^2, corresponding to the area of the projection onto the equatorial xy-plane (the base disk); this magnitude equals half the scalar surface area of the hemisphere, which is $2\pi R^2.^[12] For closed surfaces, the total vector area vanishes due to symmetry and the divergence theorem applied to the constant vector field \mathbf{c}, yielding \oint_S \mathbf{c} \cdot d\mathbf{S} = \int_V \nabla \cdot \mathbf{c} \, dV = 0, implying \oint_S d\mathbf{S} = \mathbf{0}; this contrasts with the positive scalar area of the enclosed volume's boundary.^[13]

Key Properties

Magnitude and Direction Conventions

The magnitude of a vector area \mathbf{A} is defined as the positive scalar value A = |\mathbf{A}|, representing the geometric area of the surface, and remains independent of the chosen orientation.^[14] The direction of \mathbf{A} is perpendicular to the surface, pointing along the normal vector to the positive side, determined by the right-hand rule applied to the boundary traversal: curling the fingers of the right hand in the direction of the boundary yields the thumb pointing in the direction of the normal.^[14] For a planar surface in the xy-plane with positive orientation (counterclockwise boundary traversal when viewed from above), this convention results in a normal in the positive \hat{z} direction.^[15] In two-dimensional projections, the sign of the z-component of \mathbf{A} depends on the winding order of the boundary: counterclockwise traversal produces a positive component, while clockwise yields a negative one, though the unsigned area is always the absolute value.^[14] For non-orientable surfaces like the Möbius strip, a global consistent normal vector field cannot exist, as traversing a closed path reverses the orientation; instead, local normals are defined at each point using tangent vectors and cross products, allowing piecewise computation of vector areas.^[16] The concept of vector area, unifying scalar area with directional properties via these conventions, was introduced by J. Willard Gibbs in his late 19th-century lectures on vector analysis, later formalized in a 1901 textbook based on his work.^[14]

Linearity and Superposition

The vector area satisfies the linearity principle inherent to vector spaces in three dimensions, allowing for both addition and scalar multiplication operations that preserve its geometric interpretation. For two adjacent planar regions sharing a boundary, the total vector area is the vector sum \mathbf{A}_{\text{total}} = \mathbf{A}_1 + \mathbf{A}_2, where the shared boundary contributions cancel in the line integral formulation of the vector area.^[4] This cancellation occurs because the line integral around the common edge is traversed in opposite directions for each region, leading to telescoping boundaries that reduce to the outer perimeter.^[4] The resulting sum maintains the correct magnitude and direction without distortion, as vector areas transform linearly under rotations and translations, confirming their status as true vectors.^[8] Scalar multiplication follows similarly: scaling a planar region by a positive factor k > 0 produces a new vector area \mathbf{A}' = k \mathbf{A}, where the magnitude scales proportionally while the direction, determined by the surface normal via the right-hand rule, remains unchanged.^[4] For k < 0, the direction reverses, corresponding to a flip in orientation. This property arises directly from the linearity of the underlying surface integral or line integral definitions. A proof sketch of linearity stems from the integral definition of the vector area, \mathbf{A} = \frac{1}{2} \oint_{\partial S} \mathbf{r} \times d\mathbf{l}, where \partial S is the boundary curve. For superposition of regions, the integrals over internal boundaries cancel due to opposite orientations, leaving the integral over the combined exterior boundary; scalar scaling distributes over the integral operator, yielding the proportional result.^[4] As an illustrative example, consider decomposing a quadrilateral into two adjacent triangles sharing an edge. The vector area of each triangle, computed via the line integral around its perimeter, sums to the vector area of the quadrilateral, with the shared edge integrals canceling exactly, ensuring the total magnitude equals the scalar area of the quadrilateral and the direction aligns with its normal.^[4] Vector addition is commutative, so \mathbf{A}_1 + \mathbf{A}_2 = \mathbf{A}_2 + \mathbf{A}_1, independent of order; however, consistent orientation across regions is essential to avoid sign errors in the normal direction.^[8]

Computational Aspects

Calculation via Cross Product

The vector area \mathbf{A} of a planar region bounded by a closed curve can be derived from the line integral \mathbf{A} = \frac{1}{2} \oint_C \mathbf{r} \times d\mathbf{r}, where \mathbf{r} is the position vector along the boundary curve C.^[17] This integral captures the oriented area enclosed by the curve, with the direction given by the right-hand rule relative to the traversal direction. For a polygonal boundary with vertices \mathbf{r}_1, \mathbf{r}_2, \dots, \mathbf{r}_n (where \mathbf{r}_{n+1} = \mathbf{r}_1), the line integral discretizes exactly into a sum over the edges, yielding \mathbf{A} = \frac{1}{2} \sum_{i=1}^n \mathbf{r}_i \times \mathbf{r}_{i+1}.^[18] Each term \mathbf{r}_i \times \mathbf{r}_{i+1} involves the cross product of consecutive position vectors, and the result is independent of the origin due to the closed path property, as shifting all \mathbf{r} by a constant vector adds canceling terms. This formulation reduces the computation to simple vector operations on vertex coordinates. In two dimensions, where the polygon lies in the xy-plane, the z-component of the vector area corresponds to the signed scalar area, extending the shoelace formula: A_z = \frac{1}{2} \sum_{i=1}^n (x_i y_{i+1} - x_{i+1} y_i).^[19] This expression arises directly from the z-component of the cross product, \mathbf{r}_i \times \mathbf{r}_{i+1} = (x_i y_{i+1} - x_{i+1} y_i) \hat{\mathbf{k}}, confirming the equivalence between the vector approach and the coordinate-based shoelace method. In three dimensions, the full vector \mathbf{A} generalizes this by providing all components, with the magnitude |\mathbf{A}| equal to the scalar area and the direction normal to the plane. For the simplest case of a triangle with vertices at \mathbf{r}_0, \mathbf{r}_1, and \mathbf{r}_2, the vector area simplifies to \mathbf{A} = \frac{1}{2} \mathbf{u} \times \mathbf{v}, where \mathbf{u} = \mathbf{r}_1 - \mathbf{r}_0 and \mathbf{v} = \mathbf{r}_2 - \mathbf{r}_0 are edge vectors from one vertex./01:_Vectors_in_Euclidean_Space/1.04:_Cross_Product) This follows from applying the polygon sum formula, where intermediate terms cancel, leaving the cross product of the two sides scaled by $1/2. Polygons can be decomposed into such triangles via linearity, summing their vector areas to obtain the total \mathbf{A}. This cross product method is exact for planar polygons, assuming all vertices are coplanar; deviations from coplanarity introduce errors, as the formula implicitly projects onto a single plane.^[18] In practice, coplanarity can be verified by checking that the cross products of consecutive edge vectors align in direction. The approach is widely implemented in software, particularly in CAD systems and vector graphics libraries, where it enables efficient computation of surface normals and areas for polygonal models using standard vector operations.^[18]

Numerical Methods for Complex Shapes

For complex shapes that are not simple polygons, direct analytical computation of the vector area becomes infeasible, necessitating numerical approximation techniques that discretize the surface and leverage the linearity of the vector area integral. These methods approximate the surface integral \iint_S d\mathbf{S} by breaking it into manageable parts, ensuring convergence to the exact value as resolution increases.^[20] The triangulation method decomposes the complex surface into a finite mesh of non-overlapping triangles, computes the vector area \mathbf{A}_i = \frac{1}{2} (\mathbf{r}_2 - \mathbf{r}_1) \times (\mathbf{r}_3 - \mathbf{r}_1) for each triangle using the cross product of edge vectors from a common vertex, and sums the results \mathbf{A} = \sum_i \mathbf{A}_i to exploit the superposition property. This approach is widely used in computational geometry and aerodynamics for handling irregular or scanned surfaces, with accuracy improving as the mesh density increases to better capture curvature.^[21]^[22] For arbitrary or implicitly defined surfaces where meshing is challenging, Monte Carlo integration estimates the vector area by randomly sampling points across the parameter domain (u, v) and averaging the integrand \mathbf{r}_u \times \mathbf{r}_v, yielding \mathbf{A} \approx \frac{1}{N} \sum_{k=1}^N (\mathbf{r}_u \times \mathbf{r}_v)|_{(u_k, v_k)} \Delta u \Delta v with variance decreasing as $1/\sqrt{N}. This stochastic method is particularly effective for high-dimensional or noisy data, as demonstrated in manifold sampling applications, though it requires importance sampling to reduce variance for non-uniform distributions.^[23] In the finite element approach, the surface is partitioned into small parametric patches (e.g., bilinear quadrilaterals or higher-order elements), where local vector areas are computed by integrating the normal contributions over each patch using basis functions, then aggregated globally; the approximation error is bounded by the mesh resolution h, typically O(h^k) for polynomial degree k. This method excels in error estimation and adaptivity for engineering simulations involving curved geometries.^[24]^[25] As an illustrative example, approximating the vector area of a torus—a closed surface—via polygonal meshing with thousands of triangles yields a net vector near zero, consistent with the theoretical result that the total vector area of any closed orientable surface vanishes due to pairwise cancellation of opposing normal contributions.^[26] To enhance efficiency for smooth surfaces, adaptive quadrature refines the integration grid in regions of high curvature by subdividing intervals based on local error estimates, significantly reducing computational time compared to uniform sampling while maintaining accuracy for the vector area integral.^[27]^[28]

Physical and Geometric Applications

Area Projection and Orthogonal Components

The projected area of a surface onto a plane with unit normal vector \hat{n} is given by A_{\mathrm{proj}} = |\mathbf{A} \cdot \hat{n}|, where \mathbf{A} is the vector area; this formula yields the area of the orthogonal shadow formed when the surface is illuminated by rays parallel to \hat{n}.^[29] The vector area \mathbf{A} decomposes into orthogonal components \mathbf{A} = (A_x, A_y, A_z), with each component representing the signed projected area onto the corresponding coordinate plane: A_x onto the yz-plane, A_y onto the xz-plane, and A_z onto the xy-plane.^[30] This decomposition facilitates resolving complex surface areas into mutually perpendicular parts for geometric analysis. In structural engineering, such projections are applied to determine effective areas for load distribution, where forces act perpendicular to specific planes.^[31] For instance, consider a slanted roof fitted with solar panels; the vertical component \mathbf{A} \cdot \hat{z} equals the effective horizontal projected area, essential for computing insolation based on horizontal solar radiation measurements.^[32] For a planar surface, the magnitude |\mathbf{A}| equals the scalar area of the surface, consistent with conventions for vector area interpretation. When viewed along the direction of \mathbf{A}, the silhouette area of the surface matches |\mathbf{A}|, as the projection onto a plane perpendicular to this direction has a cosine factor of 1.^[29]

Flux Calculations in Vector Fields

In vector calculus, the flux of a vector field \mathbf{F} through a surface S quantifies the net flow of the field across the surface, defined as the surface integral \Phi = \iint_S \mathbf{F} \cdot d\mathbf{A}, where d\mathbf{A} is the vector area element with magnitude equal to the infinitesimal area and direction normal to the surface.^[33] For a flat surface with a uniform vector field, this simplifies to \Phi = \mathbf{F} \cdot \mathbf{A}, where \mathbf{A} is the total vector area of the surface, representing the dot product of the field with the surface's effective area vector.^[33] This formulation highlights how the flux depends on the component of \mathbf{F} perpendicular to the surface, scaled by the surface's area. For non-uniform vector fields, where \mathbf{F} varies across the surface, the exact flux requires evaluating the full surface integral \iint_S \mathbf{F} \cdot d\mathbf{A}.^[33] An approximation can be obtained by using the average field \mathbf{F}_{avg} over the surface, yielding \Phi \approx \mathbf{F}_{avg} \cdot \mathbf{A}, which is useful for estimating flow in regions of gradual variation.^[33] The divergence theorem provides a powerful connection for closed surfaces, stating that the total flux through a closed surface enclosing a volume V is \oint \mathbf{F} \cdot d\mathbf{A} = \iiint_V \nabla \cdot \mathbf{F} \, dV, linking surface flux to the field's divergence within the volume.^[34] For any closed surface, the net vector area integrates to zero, \oint d\mathbf{A} = 0, as demonstrated by applying the divergence theorem to a constant field, ensuring that uniform fields yield zero net flux through closed surfaces absent sources.^[34] A representative example is the flux of a uniform velocity field \mathbf{v} (modeling fluid flow) through a flat window surface, where the flux \Phi = v A \cos \theta equals the field's strength times the projected area component normal to the flow direction, giving the volume flow rate in cubic units per time.^[33] The units of flux are those of the vector field multiplied by area; for instance, in magnetic fields, flux is measured in webers (Wb), equivalent to tesla-square meters (T·m²).^[33]

Advanced Uses

In Electromagnetism

In electromagnetism, the vector area \mathbf{A} plays a pivotal role in quantifying magnetic flux, defined as \Phi_B = \mathbf{B} \cdot \mathbf{A} for a uniform magnetic field \mathbf{B} passing through a surface, where \mathbf{A} has magnitude equal to the surface area and direction normal to the surface following the right-hand rule.^[35] This dot product captures the component of the field perpendicular to the surface, making it central to Faraday's law of induction and Gauss's law for magnetism. For current-carrying loops, such as in circuits, \mathbf{A} is derived from the loop's geometry, with its direction determined by the current's sense via the right-hand rule.^[36] Faraday's law states that the induced electromotive force (EMF) \mathcal{E} in a closed loop equals the negative rate of change of magnetic flux: \mathcal{E} = -\frac{d\Phi_B}{dt}.^[37] Changes in \mathbf{A}, such as through the motion of a coil in a magnetic field, directly alter \Phi_B and thus induce the EMF, as seen in generators where rotating loops vary the effective area projection.^[38] This principle underpins electromagnetic induction, where the vector nature of \mathbf{A} ensures the flux accounts for orientation relative to \mathbf{B}. The vector area also features in the magnetic moment \vec{m} = I \vec{A} of a current loop, where I is the current, representing the loop's dipole strength and orientation.^[39] In the Lorentz force context, this leads to torque on the loop in a magnetic field: \boldsymbol{\tau} = \mathbf{m} \times \mathbf{B}, which drives the operation of electric motors by aligning the moment with the field. A practical example is the magnetic flux calculation in a solenoid, where the vector area \mathbf{A} of the cross-sectional end face (perpendicular to the axis) yields \Phi_B = B A, with B = \mu_0 n I inside, n the turns per unit length, and \mu_0 the permeability of free space; the cylindrical lateral surface has \mathbf{A} perpendicular to \mathbf{B}, resulting in zero flux contribution.^[40] The formalization of vector area in electromagnetic field integrals traces to James Clerk Maxwell's equations in the 1860s, where surface integrals over vector areas enabled the unification of electric and magnetic phenomena through flux concepts.

In Computer Graphics and Visualization

In computer graphics, the vector area of a triangular face is computed as half the cross product of two edge vectors, yielding a vector whose magnitude represents the scalar area and whose direction indicates the surface normal.^[41] Normalizing this vector area by its magnitude produces the unit surface normal, which is crucial for shading algorithms like the Phong reflection model, where it determines diffuse and specular lighting contributions based on angles between the normal, light direction, and view direction.^[42] This approach ensures realistic illumination by aligning light interactions with the oriented surface geometry. Backface culling optimizes rendering by discarding polygons facing away from the viewer, achieved by computing the dot product of the surface normal—derived from the vector area—with the vector from a point on the polygon to the viewpoint; a negative result indicates the face is back-facing and invisible.^[43] This test reduces unnecessary rasterization, improving performance in real-time applications without altering visible output. In ray tracing, vector areas aid global illumination by quantifying oriented intersection fluxes, enabling accurate computation of light transport between surfaces for effects like indirect bounces and caustics.^[44] Modern engines such as Unity and Blender leverage vector areas in mesh processing, automatically computing normals via cross products for shading and supporting GPU acceleration through fragment and vertex shaders that perform these operations in parallel.^[45]

References

[1]
Area Vectors - Front Matter
Definition 22.2.1. Area Vector. The area vector A → for a surface points perpendicular to the surface, with a magnitude equal to the area of the surface.
[2]
Vector algebra - Richard Fitzpatrick
In applied mathematics, physical quantities are (predominately) represented by two distinct classes of objects. Some quantities, denoted scalars, ...<|control11|><|separator|>
[3]
The vector product - Richard Fitzpatrick
The cross product transforms like a vector, which means that it must have a well-defined direction and magnitude. We can show that ${\bf a}\times{\bf b}$ is ...
[4]
[PDF] Vector Analysis
If S happens to be flat, then. |a| is the ordinary (scalar) area, obviously. (a) Find the vector area of a hemispherical bowl of radius R. (b) Show that a = 0 ...
[5]
3. Magnetostatics - Galileo and Einstein
where we've introduced the vector area s of the surface S bounded by C, defined as ... now with the magnetic dipole moment ... where m is the magnetic dipole moment ...
[6]
[PDF] Traditional Vector Theory
Nov 9, 2013 · In applications with traditional vectors ... (The concept of “vector area” can be relevant in computations of certain surface integrals.).
[7]
[PDF] Electromagnetism and Optics - Richard Fitzpatrick
the vector area of a given surface is completely determined by its rim. So, two different surfaces sharing the same rim both possess the same vector area.
[8]
Vector areas - Richard Fitzpatrick
Suppose that we have planar surface of scalar area $S$ . We can define a vector area ${\bf S}$ whose magnitude is $S$ , and whose direction is perpendicular ...Missing: "vector
[9]
https://www.hlevkin.com/hlevkin/90MathPhysBioBooks/Physics/Physics/Electrodynamics/David%20J.%20Griffiths%20-%20Introduction%20to%20Electrodynamics-Prentice%20Hall%20(1999).pdf
[10]
[PDF] Contents 1 Vectors and 3-Dimensional Geometry - Evan Dummit
Example: Find the area of the triangle whose vertices are the points A(1, −1, 2), B(2, −3, 1), and C(2, 2, 2). ◦ By the Cross Product Theorem, the area ...
[11]
[PDF] Line, Surface and Volume Integrals
The vector area of a surface S is defined as. S = ∫. S. dS. Example. Find the vector area of the surface of the hemisphere x2 + y2 + z2 = a2 with z ≥ 0. 28 ...
[12]
[PDF] Solutions
... line integral ... Hint: The vector area of a closed surface is zero. The vector area of a closed surface is zero. Let the vector area of the curved surface be SC.
[13]
[PDF] Vector analysis; a text-book for the use of students of mathematics ...
J. WILLARD GIBBS. Yale University, September, 1901. Page 12. Page 13. GENERAL PREFACE. When I undertook to adapt the lectures of Professor Gibbs on Vector ...
[14]
Nonorientable Surface - an overview | ScienceDirect Topics
A surface M ⊂ R3 is orientable if and only if there exists a unit normal vector field on M. If M is connected as well as orientable, there are exactly two unit ...
[15]
[PDF] Griffiths: Magnetic moment
cal interpretation: (r' X dl) is the area of the shaded triangle, in Fig. 5.50, so the integral is the area of the whole loop: ± √ (r' × dl) = a. (5.81)Missing: \int \times
[16]
[PDF] • • •
... using cross product assumed that v0 and v1 lie in 3- dimensions. In fact, since v0 and v1 lie in a plane, we can always embed these vectors in a 3-.
[17]
Shoelace formula: Connecting the area of a polygon and vector ...
The Shoelace theorem gives a formula for find- ing the area of a polygon from the coordinates of its vertices.
[18]
[PDF] Computation of Sectional Loads from Surface Triangulation and ...
Computation of Sectional Loads from Surface Triangulation and. Flow ... where Tij is the stress tensor and Aj is the vector area of the current triangle.
[19]
[PDF] Surface Triangulation: A Survey - Stat@Duke
Jul 3, 1996 · Abstract. This paper presents a brief survey of some problems and solutions related to the triangula- tion of surfaces.
[20]
[PDF] Monte Carlo on manifolds: sampling densities and integrating ... - arXiv
Sep 20, 2017 · This paper presents Monte Carlo methods for computing a d-dimensional integral over a d-dimensional connected manifold M embedded in a da- ...
[21]
Finite element procedures for computing normals and mean ...
In this paper we consider finite element approaches to computing the mean curvature vector and normal at the vertices of piecewise linear triangulated surfaces.
[22]
[PDF] Numerical methods for PDEs on curves and surfaces - DiVA portal
In this thesis, we examine two numerical methods for the solu- tion of PDEs on manifolds: a so called cut finite element method and isogeometric analysis. We ...
[23]
Total Vector Area of Closed Surface is Zero - ProofWiki
Let dS be an infinitesimal vector area around some point P of S.
[24]
Numerical quadrature over smooth, closed surfaces - Journals
Oct 1, 2016 · This paper considers an RBF-based method for numerical quadrature over smooth, closed surfaces. This method is well suited for obtaining ...
[25]
[PDF] Numerical quadrature over smooth surfaces with boundaries
This paper describes a high order accurate method to calculate integrals over curved surfaces with boundaries. Given data locations that are arbitrarily ...
[26]
[PDF] Characterization of Test Mass Scattering
Sep 23, 2017 · The projected area is defined as the projection of the area vector onto a surface normal to the direction of view and is equal to the actual ...
[27]
[PDF] Notes on Flux Integrals - UNL Math
Given the surface area and normal, we can define an area vector at a point by dÃ = ñ dS. ... for projection onto the yz plane. Note that there is a simple ...
[28]
[PDF] Calculating Design Loads for Residential Structures - PDH Online
walls, and their load distribution capabilities. Only in the case ... = (roof VPA)(roof projected area pressure) + (wall VPA)(wall projected area pressure).
[29]
[PDF] Solar Photovoltaic Applications Seminar - UNT Digital Library
... projected area, as specified in the. Southern code. Factors should then' be ... tilted surface, is: 25 Ib/ft2 multiplied by the tilt factor, the area ...
[30]
Calculus III - Surface Integrals of Vector Fields
Nov 16, 2022 · In order to work with surface integrals of vector fields we will need to be able to write down a formula for the unit normal vector corresponding to the ...
[31]
6.8 The Divergence Theorem - Calculus Volume 3 | OpenStax
Mar 30, 2016 · More specifically, the divergence theorem relates a flux integral of vector field F over a closed surface S to a triple integral of the ...Missing: uniform
[32]
13.1 Faraday's Law - University Physics Volume 2 | OpenStax
Oct 6, 2016 · An emf is induced when the magnetic field in the coil is changed by pushing a bar magnet into or out of the coil. Emfs of opposite signs are ...
[33]
[PDF] Chapter 10 Faraday's Law of Induction - MIT
• A motional emf ε is induced if a conductor moves in a magnetic field. The general expression forε is. (. ) d ε = × ⋅. ∫ v B s. G. G. G v. In the case of a ...
[34]
Magnetic moment - HyperPhysics
The magnetic moment summarizes a current loop's characteristics, is a vector perpendicular to the loop, and is also called the magnetic dipole moment.
[35]
Magnetic Field inside a Solenoid — Collection of Solved Problems
Dec 11, 2017 · We assess the magnitude of the magnetic B-filed by using Ampère's law: ∫l→B⋅d→l=μoIc. We use a rectangle denoted ABCD as the Ampère's curve, ...
[36]
Area of a triangle - Inigo Quilez
As we all know, the area of a triangle defined by its 3D coordinates in space, is given by. S = ½ |ei ⊗ ej| where ⊗ is the cross product.
[37]
[PDF] Illumination for Computer Generated Pictures
This paper is concerned with the shading problem; the contour edge problem is discussed by the author and F.C. Crow in [7]. Influence of Hidden Surface ...
[38]
[PDF] Fast Backface Culling Using Normal Masks - UNC Computer Science
Typically, the backface test involves calculating the dot product between the polygon's normal and the vector formed from the viewing point to any point on ...
[39]
[PDF] Surface Parameterization: a Tutorial and Survey
This paper provides a tutorial and survey of methods for parameterizing surfaces with a view to applications in geometric modelling and computer graphics. We ...Missing: UV | Show results with:UV
[40]
[PDF] Global Illumination Compendium | CS@Cornell
Sep 29, 2003 · Direct illumination computations in ray tracing using shadow-rays also often implicitly computes a point-to-area form factor. A. GENERAL ...
[41]
Mesh Analysis - Blender 4.5 LTS Manual
The mesh analysis works in Edit Mode and Solid Viewport shading. It shows areas with a high value in red, and areas with a low value in blue.