Lowdistortion projections ldps produce mapping grids formulated so that distances obtained by inversing grid coordinates match as best as. This is an informal overview of development of low distortion projections ldps. We plan to give you the complete story behind the development of the \. Pima county low distortion projection coordinate systems. Gis design support for nsrs 2022 and low distortion.
Brief history of low distortion projections global cogo, inc. A few years ago, through the old message board, i virtually met loyal olson, a surveyor with a long history working in the rugged mountain west. The apparent effect is that of an image which has been mapped around a sphere or barrel. Coordinate systems, projections, and transformations. Here, in part 2, i will describe the actual design of two real world low distortion projections and the benefit implementing your own ldps could present in your own work. Methods for reducing projection linear distortion low distortion projections ldps the iowa regional coordinate system iarcs spatial data documentation metadata.
Indiana geospatial coordinate system ingcs grid vs. With an orthographic projection matrix, there is no depth so you might as well give up on 3d graphics in that case. With 25 % 2 more contrast and brightness of up to 4,100 lm 3, the ptlb426 series produces dynamic highvisibility images with the room lights on more information. We present a new method for interactive visualization of distortion in map projections. February 2015 this is an informal overview of development of low distortion projections ldps. Four methods for lowdistortion projections journal of surveying. Modern gis and surveying software now brings the opportunity to create low distortion map projections and coordinate systems that can relate closely to. Ldps are conformal map projections that minimize linear distortion at the. Oregon coordinate reference system state of oregon. Mathematical calculations are used to convert the coordinate system used on the curved surface of earth to one for a flat surface. I havent tried monkeying with it in a couple of years, but when creating a low distortion projection in c3d, with an oblique mercator projection, i could never get it to take the base parameters and give me the correct.
Longlife 20,000hour 4 lamp and 10,000hour 5 filter slash maintenance costs while optional early warning 6 software reinforces uncommonly high reliability. Six steps for designing a low distortion projection ldp 9. Ron dry, rls city of surprise land surveyor brian fisher, rls david evans and associates, inc. You can configure a precise lowdistortionprojection in survce quickly while in the field. Ground truth or professional land surveyors of oregon. Modern geographic information systems and surveying software now bring the opportunity to create low distortion map projections and coordinate systems that can relate closely to measure distances on the ground.
Over the years a great number of map projections have been proposed. Currently, all coordinate systems that come with civil 3d, autocad map 3d, and infraworks software are grid coordinate systems. Statewide low distortion projection design request for proposal iowa department of transportation. Oct 25, 2018 likewise, the feds would have to define their projection on a us level. A pennsylvania traverse lowdistortion projection xyht. Brief history of low distortion projections global cogo. In barrel distortion, image magnification decreases with distance from the optical axis. Example of surveying and mapping documentation metadata.
The pima county coordinate system design and documentation of a fourzone lowdistortion projection coordinate system for pima county, arizona prepared for. A tool is built on top of the interactive map projections system that provides a new method of visualizing map projection distortion. Avis, pls, gisp project manager information technology department gis division pima county 33 n stone avenue floor 15 room 15 tucson, az 85701 prepared by. The map projection selection tool was developed to help cartographers pick the best map projection for making maps in a gis software program. Longlife 20,000hour 4 lamp and 10,000hour 5 filter slash maintenance costs while optional early warning 6 software. Low distortion projection, where grid is ground city of surprise. Low distortion map projections for engineering, surveying, and gis. Dennis, phd, pe, rls august 2019 design and metadata example. Part of this preparation for the 2022 datum is a redesign of state plane coordinate system spcs zones. An iowa dot lds rfp selection committee, including representatives of the society of land surveyors of iowa and the iowa county engineers association, have evaluated and recommended selection of a proposal for design and documentation of a low distortion projection coordinate system for the state of iowa on march a. Barrel distortion may be found in wideangle lenses, and is often seen at the wideangle end of zoom lenses, while pincushion distortion is often seen in older or low end telephoto lenses. Kansas association of mappers low distortion projection for.
Wsrs2022 task force looking for additional volunteers. Help is requested in verifying the validity of the parameters. Map projection distortion is an unavoidable consequence of attempting to represent a curved surface on a flat surface. Low distortion projectionspart 2 ground versus grid. I count loyal olsen to be a good friend and drinking buddy. The iowa regional coordinate system iarcs is based on a set of 14 low distortion map projection zones ithw parameters that have been defined such that lineadir s tortion is negligible within the counties that define the zone. Contrasting a low distortion projection ldp with the. Now i may be completely wrong, but that distortion does not feel realistic. Selecting an appropriate map projection is one of the first important decisions when working and mapping out gis data. Many surveyors use custom, or lowdistortion, projections ldps to make. Oblique mercator custom projections and ocrs low distortion projections looks like i missed answer day, but ill ask anyway.
Wsrs2022 task force looking for additional volunteers state. The iowa regional coordinate system iowa state university. The oregon coordinate reference system component of the online toolkit allows users to determine the best low distortion projection zone for their project. With a projection set, the program will adjust the ground measurements to be in common with the grid, process the entire network and allow you to export to a separate scaled coordinate file. Converting a sphere to a flat surface results in distortion. Oregon has regional low distortion projection zones established that minimize distortion based on topography. Prefinal statewide 8,515kb pdf prefinal ldp zones 4,999kb pdf prefinal statistics 528kb pdf. Provide past performance on contracts in terms of cost control, quality of work, and compliance with performance schedules. We are hopeful that kdot will be able to present on this topic at kam 2019, so stay tuned for details. Post processing gps software has supported custom projections for years. A projection is the means by which you display the coordinate system and your data on a flat surface, such as a piece of paper or a digital screen. This includes the development of low distortion projection zones and a state. Ground truth for the future low distortion projections and the state plane coordinate system of 2022 michael l. An iowa dot lds rfp selection committee, including representatives of the society of land surveyors of iowa and the iowa county engineers association, have evaluated and recommended selection of a proposal for design and documentation of a low distortion projection coordinate system for the state of iowa on march.
In this class, well explore the creation of a custom ground coordinate system in civil 3d software and autocad map 3d software. Imagine a map projection as an attempt to reconstruct your face in two dimensions. A low distortion projection ldp is typically based on a conformal projection that covers only a small portion of the earths surface and, the design parameters of a ldp are chosen such that the transformed latitudelongitude position. Low distortion projections ldps minimize this distortion by covering the largest area with the least amount of distortion possible.
With that said, well create whats called a low distortion projection ldp. Iowa also has regional low distortion projection zones. The rocky mountain tribal coordinate reference system is based on a group of low distortion map projection coordinate systems. Shawn billings excellent article in american surveyor on low distortion projections. Weve just added a link in our information exchange to the kansas regional coordinate system krcs documentation on the dasc website. It is also important to mention that several states and countries have adopted low distortion projections ldp which basically breaks up the area into.
Ocrs bendredmondprineville noaas national geodetic survey oklahoma society of land surveyors broken arrow, ok august 23, 2019. Well pick a mean elevation for this ldp, which will. The central idea is a floating ring on the globe that can be interactively positioned and scaled. The v60s, v90s and v315s all have identical dimensions enabling them to be flown in the same vertical array.
As the ring is manipulated on the globe, the corresponding projection of the ring is distorted using the same map projection parameters. As the ring is manipulated on the globe, the corresponding projection of the ring is distorted using. It can be thought of as a change in the true relationship between. Each reprojection to a larger area will introduce distortion. The system the vero range features six highlyefficient, low distortion hornloaded loudspeakers the v60 midhigh, v90 midhigh and v315 midbass with a choice of v221, v124 or v2 bass. Likewise, the feds would have to define their projection on a us level. Design of rigorously defined low distortion projections compatible with a wide range of software packages. Eliminates the issues with a modified datum works seamlessly with modern software regional approach reduces the number of transition zones may be accepted by ngs modern low distortion projection ldp system.
Apls is happy to report that we have met our fundraising goal for the low distrortion design software. As demands for precise measurement of land and natural resources increase, todays data users must sharpen their focus on 1 understanding historical measurements, 2 embracing emerging measurement and mapping technology, and 3 planning our collective future. The function of low distortion projections is to minimize the distortions of angles, azimuths, distances, and areas. Low distortion projection nd gis north dakota geographic. Projection grid distance difference ppm world mercator 7,626. They can also view the actual distortion of a particular ocrs zone near their project by placing a point, line or polygon on the map. For those who are unfamiliar with this, the krcs is a low distortion coordinate system that was created at kdots request to eliminate the need for scale factors when converting from state plane to ground coordinates.
Oblique mercator custom projections and ocrs low distortion. Low distortion projections are based on true conformal map projections designed to cover significant portions of urban and rural areas of the state. Low distortion projections for montana geonet, the esri. The idea is to architect the arcgis platform and the geodatabasefeature dataset containers to allow feature data to remain in the low distortion projections. Even for the skilled cartographer, who has a good knowledge of map projection principles.
Low distortion projection tools additions to the geodetic tool kit brought to you by dave minkel and michael dennis low distortion projections what are we talking about. Low distortion projections ldps geodetic analysis, llc. A mapping projection that minimizes the difference between distances depicted in a gis when compared to the realworld distances at ground. Ground truth design and documentation of low distortion projections for surveying and gis. Design and documentation of low distortion projections for surveying and gis january 2015 page 2 what is map projection distortion. Anyone who has spent time working with map projections knows that you cant have both a large area and low distortion. Apls raised funds to purchase an annual lease of low distortion projection ldp design software. This projection will have the advantage of being aligned to true geodetic north at the base point and will effectively have a scale factor of 1. The low distortion projection project is a work in progress. Modern gis and surveying software now brings the opportunity to create low distortion map projections and coordinate systems that can relate closely to measured distances on the ground. Each re projection to a larger area will introduce distortion. Ground versus grid by shawn billings, ps blue marble geographic calculator provides an incredible variety of tools for working with an infinite combination of datums and projections.
Shown here, ive entered the parameters for a low distortion projection for my home town. We offer a wide range of geodetic consulting, gis, and educational services throughout the u. Ldps are map projection optimizations that take into account the combined effect of earths curvature and ground height above the ellipsoid. Contrasting a low distortion projection ldp with the global. This includes the development of low distortion projection zones and a state plane coordination system of 2022. The oregon coordinate reference system component of the online toolkit allows users to determine the best lowdistortion projection zone for their project. Low distortion projections contains geographically projected coordinate systems designed for low distortion applications. Using the iarcs in software distortion calculations most important. As more states move toward low distortion projections, the need to reduce gridtoground distances will diminish. A north dakota committee was formed in 2018 to address this change and to provide input. City of surprise coordinate system a low distortion projection presented by. However, while my perspective projection seemed to work great at first, i noticed something when i translated my cube away from the center of the projection. Low distortion projection larger zones with similar performance to cntycoord.
I briefly outlined five surfaces of which surveyors should be aware ellipsoid, topographic, geoid, design and developed. Mustache distortion is observed particularly on the wide end of zooms, with certain retrofocus lenses, and more recently on largerange zooms such as the. Hes been using ldps in his work for decades, originally using software written for a wang computer in the 1970s. Mar 14, 2017 the low distortion projection project is a work in progress.
The objective of an ldp is to cover the largest area with the least distortion possible. Brief history of low distortion projections earl f. Fisheye lenses, which take hemispherical views, utilize this type of distortion as a way to map an infinitely wide object plane into a finite image area. Second, select an ldp that works with as many kinds of survey and mapping equipment and software as possible. Pima county low distortion projection coordinate systems pccs.
This is the most profound single fact about map projectionsthey distort the worlda fact that you will investigate in more detail in module 4, understanding and controlling distortion. Kansas association of mappers low distortion projection. Modeling projection projection is a matrix multiply using homogeneous coordinates. This workshop includes a discussion of map projection types, explanation of projection distortion, detailed instructions on optimal design of an ldp covering an area as large as possible, guidance on defining coordinate systems for data transferability, and the important issues of.
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