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Topic: Oblique projection


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In the News (Thu 26 Nov 09)

  
  Map projection - Wikipedia, the free encyclopedia
Unavoidably, all cylindrical projections have an east-west stretching away from the equator by a factor equal to the secant of the latitude, compared with the scale at the equator.
Azimuthal projections have the property that directions from a central point are preserved (and hence, great circles through the central point are represented by straight lines on the map).
Some azimuthal projections are true perspective projections; that is, they can be constructed mechanically, projecting the surface of the Earth by extending lines from a points of perspective (along an infinite line through the tangent point and the tangent point's antipode) onto the plane.
en.wikipedia.org /wiki/Map_projection   (2634 words)

  
 Graphical projection -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-17)
Graphical projection is a protocol by which an image of an imaginary three-dimensional object is projected onto a plane surface by the use of imaginary "projectors".
Orthographic projection is derived from the principles of (The geometry of properties that remain invariant under projection) descriptive geometry and may produce an image of a specified, imaginary object as viewed from any direction of space.
In oblique projections parallel projectors are imagined to emanate from all points of an imaginary object and which strike the projection plane at an angle other than ninety degrees - as opposed to orthographic projectors, which strike the plane of projection at ninety degrees.
www.absoluteastronomy.com /encyclopedia/g/gr/graphical_projection.htm   (860 words)

  
 Oblique projection - Wikipedia, the free encyclopedia
In orthographic projection and oblique projection, parallel lines in space appear parallel on the projected image.
In orthographic projection, a = b = 0, in other cases it is oblique projection.
In an oblique pictorial drawing, the angles displayed among the axes, as well as the foreshortening factors (scale) are arbitrary.
en.wikipedia.org /wiki/Oblique_projection   (234 words)

  
 PlaneView 3D Planar Geometric Projections Tutorial
Orthographic projections are one of two projection types derived by subdivision of the parallel projection subclass.
To project the top view of the 3-D object, the y-coordinates are discarded and the x- and z-coordinates for each point are mapped to the viewplane.
Trimetric projections have a potential disadvantage in that measurement of lines along the axes is difficult because of a difference in scaling factors.
www.mtsu.edu /~csjudy/planeview3D/tutorial-parallel.html   (1273 words)

  
 Criteria for Choosing a Map Projection   (Site not responding. Last check: 2007-10-17)
Projection is mathematically based on a cone that is tangent at one parallel or conceptually secant at two parallels.
Sinusoidal equal-area projection is mathematically based on a cylinder tangent on the equator and is used as an equal-area projection to portray areas that have a maximum extent in a north-south direction.
In the secant case of the transverse Mercator projection, lines of equal-scale difference (parallels of the graticule in the normal aspect Mercator's projection) are small circles parallel to the central meridian.
hcgl.eng.ohio-state.edu /~yi/map636/group61.htm   (2248 words)

  
 Map Projection Overview
Map projections are attempts to portray the surface of the earth or a portion of the earth on a flat surface.
Oblique Projection of a Sphere onto a Cylinder (Tangent Case)
A Lambert Conformal Conic Projection was proposed with an origin at 31:10 North, 100:00 West and with standard parallels at 27:25 North and 34:55 North.
www.colorado.edu /geography/gcraft/notes/mapproj/mapproj.html   (1829 words)

  
 Projection Parameters
Oblique Mercator (Hotine) A. Used primarily for mapping regions with an extent in the oblique direction and was used (before SOM) for mapping Landsat data.
This projection uses two points that are on the central line and are near the edges of the region.
Oblique Mercator (Hotine) B. Used primarily for mapping regions with an extent in the oblique direction and was used (before SOM) for mapping Landsat data.
edcsns17.cr.usgs.gov /helpdocs/parameters/parameters.html   (1421 words)

  
 Projections and Projected Coordinate Systems   (Site not responding. Last check: 2007-10-17)
It has been noted that the Transverse Mercator projection is employed for the topographical mapping of longitudinal bands of territories, limiting the amount of scale distortion by limiting the extent of the projection either side of the central meridian.
The projection's initial line may be selected as a line with a particular azimuth through a single point, normally at the center of the mapped area, or as the geodesic line (the shortest line between two points on the ellipsoid) between two selected points.
In the special case of the projection covering the Alaskan panhandle the azimuth of the line at the natural origin is taken to be identical to the azimuth of the initial line at the projection centre.
www.posc.org /Epicentre.2_2/DataModel/ExamplesofUsage/eu_cs34i.html   (939 words)

  
 Everywhere Displays: Technology
To correct the distortions caused by oblique projection and by the shape of the projected surface (if not flat), the image to be projected must be inversely distorted prior to projection.
In a typical situation of oblique projection, the pattern shown in the top-left is projected without any correction, resulting in the bottom-left image.
In this case, calibration is obtained by interactively grabbing with the mouse each corner of the projected pattern and moving it to the desired location on the surface.
www.research.ibm.com /ed/ed_technology.htm   (1271 words)

  
 Map Projections: Oblique projections
August's conformal projection, both with 15°E, 70°S as the map center: very few oceanic sites (notably the Caribbean sea) are interrupted, and relative sizes of oceans are clearly expressed.
Oblique maps often make this kind of distortion obvious: notice the New Zealand islands in the Atlantis map, and the east and west coasts of North America in Spilhaus's maps.
A similar, very simple modification of Hammer's projection was published by William Briesemeister in 1948: the map is first projected obliquely with 10°E 45°N as the central point; then it is linearly stretched to an aspect ratio of 7 : 4 (compare with 2 : 1 for both Mollweide and conventional Hammer).
www.progonos.com /furuti/MapProj/Dither/ProjObl/projObl.html   (820 words)

  
 EPSG Guidance Note 7
For the stereographic projection the origin is at the centre of the projection where the plane of the map is imagined to be tangential to the ellipsoid.
For Conical map projections, which for the normal aspect may be considered as the projection of the ellipsoid onto an enveloping cone in contact with the ellipsoid along a parallel of latitude, the parallel of contact is known as a standard parallel and the scale is regarded as true along this parallel.
The projection's initial line may be selected as a line with a particular azimuth through a single point, normally at the centre of the mapped area, or as the geodesic line (the shortest line between two points on the ellipsoid) between two selected points.
remotesensing.org /geotiff/proj_list/guid7.html   (8993 words)

  
 Hotine Oblique Mercator   (Site not responding. Last check: 2007-10-17)
The EPSG Projection Oblique Mercator with code 9815 indicates that it's formula is really just that of Hotine Oblique Mercator despite the slightly different naming of the false easting and northing.
EPSG considers the Oblique Mercator and Hotine Oblique Mercator projections as two very similar but separate methods because there is a subtle difference regarding the point at which the rectification from skew grid to map grid and where the false grid coordinates are applied.
The projection's initial line may be selected as a line with a particular azimuth through a single point, - normally at the centre of the mapped area - or as the geodesic line (the shortest line between two points on the ellipsoid) between two selected points.
www.remotesensing.org /geotiff/proj_list/hotine_oblique_mercator.html   (1559 words)

  
 B_ch6
Oblique projection is a form of parallel projection in which the projectors are parallel to each other but are not perpendicular to the projection plane.
In oblique projection, first, the object face that is placed parallel to the frontal plane will be drawn true size and shape.
In oblique drawings, dimensions lie in the plane of the surface to which they apply, and unidirectional text placement is used.
www.et.byu.edu /~msaito/CE112/B_ch6.html   (387 words)

  
 6.3.4 Oblique Mercator (-Jo -JO)   (Site not responding. Last check: 2007-10-17)
Oblique configurations of the cylinder give rise to the oblique Mercator projection.
It is particularly useful when mapping regions of large lateral extent in an oblique direction.
The projection was developed in the early 1900s by several workers.
gmt.soest.hawaii.edu /gmt/doc/html/GMT_Docs/node84.html   (204 words)

  
 CIRCLES IN OBLIQUE
Figure 5-55.-Cavalier projection of a circle on a receding
projection, a circle on the surface parallel to the
projection in which the circle appears as an ellipse.
www.tpub.com /content/engineering/14069/css/14069_180.htm   (257 words)

  
 Applying a Map Projection   (Site not responding. Last check: 2007-10-17)
A map projection establishes the axis type and coordinate conversion mechanism for mapping points on the earth's surface, expressed in latitude and longitude, to points on a plane, according to one of several possible map projections.
Scale factor at the central meridian (for the Transverse Mercator projection) or the center of the projection (for the Hotine Oblique Mercator projection)
The map projection properties are normally taken from the currently selected dataspace.
idlastro.gsfc.nasa.gov /idl_html_help/it_maps5.html   (550 words)

  
 Orthographic and Oblique Projection
the object and its plane of projection, the projectors
the plane of projection as in figure 3-4.
projection) is parallel to the plane of projection.
www.tpub.com /content/draftsman/14040/css/14040_38.htm   (257 words)

  
 CSDGM - 4 : Spatial Reference Information
4.1.2.1 Map Projection -- the systematic representation of all or part of the surface of the Earth on a plane or developable surface.
4.1.2.1.23.11 Oblique Line Azimuth -- method used to describe the line along which an oblique mercator map projection is centered using the map projection origin and an azimuth.
4.1.2.1.23.12 Oblique Line Point -- method used to describe the line along which an oblique mercator map projection is centered using two points near the limits of the mapped region that define the center line.
www.fgdc.gov /metadata/csdgm/04.html   (2309 words)

  
 Oblique Projection Methods.
The approximate problem obtained for oblique projection methods has the potential of being much worse conditioned than with orthogonal projection methods.
Therefore, one may wonder whether there is any need for using oblique projection methods.
As will be seen later, there are also methods based on oblique projection techniques which require far less storage than similar orthogonal projections methods.
www.cs.utk.edu /~dongarra/etemplates/node81.html   (226 words)

  
 oblique
pertaining to muscles running obliquely in the body as opposed to those running transversely or longitudinally.
Latin genitive, dative, accusative, and ablative cases are said to be oblique.
any of several oblique muscles, esp. in the walls of the abdomen.
www.infoplease.com /dictionary/oblique   (193 words)

  
 [No title]   (Site not responding. Last check: 2007-10-17)
A study of axonometric, oblique and perspective projections.
Upon completion of the course the student will be able to interpret data to draw cavalier oblique drawings.
Upon completion of the course the student will be able to interpret data to determine the appropriate position in which to place object in oblique projection.
www.kckcc.cc.ks.us /syllabi/doc/ENGR0154.DOC   (1603 words)

  
 Obliq parallel projection   (Site not responding. Last check: 2007-10-17)
Oblique projections have their projectors that are NOT perpendicular to the projection plane i.e.
  Cavalier parallel projections -- The lines perpendicular to projection plane are preserved in length, that is, L=1
  More oblique projections -- Changing the values of L produce different oblique projections.
www.cs.fit.edu /wds/classes/cse5255/thesis/obliq/obliq.html   (63 words)

  
 Spatial Reference info: FGDC metadata content standard
method used to describe the line along which an oblique mercator map projection is centered using two points near the limits of the mapped region that define the center line.
a complete description of a projection, not defined elsewhere in this standard, that was used for the data set.
The information provided shall include the name of the projection, the names of the parameters and values used for the data set, and the citation of the specification for the algorithms that describe the mathematical relationship between the Earth and the plane or developable surface for the projection.
geology.usgs.gov /tools/metadata/standard/04.html   (1620 words)

  
 esm_giesecke_8|Engineering Graphics|Essay Questions|Chapter 18 - Oblique Projection
To create paragraphs in your essay response, type

at the beginning of the paragraph, and

at the end.
Which is the most photorealistic: isometric, perspective, or oblique projection?
If a hockey puck were to be drawn using oblique projection, how should it be positioned to appear as a circle?
wps.prenhall.com /esm_giesecke_8/0,8217,1004445-,00.utf8.html   (378 words)

  
 Oblique Projection
So long as basic rules are followed, oblique projection is quite easy to master and it may be a suitable style for you to use in a design project.
Example of a basic design for a camera, drawn in oblique projection.
Draw an item of your choice using oblique projection - for example - a personal stereo.
www.technologystudent.com /designpro/oblique1.htm   (217 words)

  
 Oblique Depth Projection (D3D)   (Site not responding. Last check: 2007-10-17)
The following code modifies the D3D projection matrix so that the near plane coincides with a given arbitrary plane.
This code assumes that the original projection matrix is a perspective projection (standard or infinite).
Modifying the projection matrix to perform oblique near-plane clipping.
www.terathon.com /code/obliqued3d.html   (129 words)

  
 Oblique Projection - Cylinders
In comparison with other ways of drawing cylinders (for example, perspective and isometric) using oblique projection is relatively easy.
Draw a vertical and horizontal centre lines to indicate the centre of a circle, then use a compass to draw the circle itself.
Remember the general rule for oblique is to half all distances projected backwards.
www.technologystudent.com /designpro/oblique2.htm   (154 words)

  
 Oblique Projection Methods for Large Scale Model Reduction   (Site not responding. Last check: 2007-10-17)
Oblique Projection Methods for Large Scale Model Reduction
Oblique Projection Methods for Large Scale Model Reduction:SIAM Journal on Matrix Analysis and Applications Vol.
The aim of this paper is to consider approximating a linear transfer function $F(s)$ of McMillan degree $N$, by one of McMillan degree $m$ in which $N\gg m$ and where $N$ is large.
epubs.siam.org /sam-bin/dbq/article/25074   (250 words)

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