News

The CaGIS Board is calling for nominations to the Board to serve starting spring of 2023. 

There are 3 positions open: the Vice President, and two Director positions. Membership on the CaGIS board requires current membership in CaGIS while serving on the Board. The CaGIS bylaws state that the Vice President position for this next year be filled with a person in academia. However, if such a person cannot be recruited the position can be filled by a member from the government or in the private sector. The two director positions are open to anyone in academia, government or private sector. The two persons rotating off the board are from government, so we are especially looking for candidates from government or the private sector to maintain representation from all of CaGIS’s constituencies.

The responsibilities and expectations of these positions are as follows:

The Vice-President shall be elected by the Voting Members for a term of one (1) year. The Vice President shall preside at the meetings of the Society and of the Board in the absence of the President and President Elect, and discharge the duties of the President in the event of disability or in case of a vacancy in both that office and the office of President Elect. 

The Vice President shall automatically succeed to the position of President Elect for a term of one (1) year at the end of their term as Vice President, and then automatically succeed to the position of President for one (1) year at the end of their term as President Elect, and then automatically succeed to the position of Past President for one (1) year after their term as President.

Directors shall be elected for four (4) – year terms by Voting Members. The term of the Directors shall be staggered so that no more than three (3) Directors are elected in any one-year. No more than three (3) Directors may be employed by the Federal Government at the time of their election. A director may serve no more than two consecutive terms on the Board. The Directors shall aid in the management of the affairs of the Society, shall furnish counsel, and shall participate in all official actions of the Board.

Board Responsibilities:

The primary responsibility is conducting the activities of the Society. The Board has the authority to determine policies and procedures of the Society; providing such actions are in conformity with the provisions of the CaGIS By-Laws. The President, in consultation with the Executive Director, Treasurer, the President Elect, and the Vice President, shall prepare an annual budget including dues paid annually by the members to cover costs of Society programs and activities. The President shall submit the budget to the Board for approval.

Please contact Thomas Pingel (tpingel@vt.edu, Chair of the Nominations Committee) with nominations by replying to this email. Self nominations are welcome. Nominees must submit a brief bio, and a statement of their interest and what they could contribute to CaGIS and the Board.

The deadline for receiving this information is Nov 15.

John Dolloff and Hank Theiss will be presenting “Principles of Accuracy and Predicted Accuracy in Photogrammetric-based Geopositioning” at the next GeoBytes webinar on Friday, October 21 at 12:00 pm ET. The webinar is FREE for all CaGIS members. See attached abstract for more information about the presentation.

Please see the CaGIS GeoBytes page for more information on registering.

Abstract

This webinar addresses the importance and use of both accuracy and predicted accuracy in a Geolocation System. Accuracy is typically represented as a LE90, CE90, and/or SE90 corresponding to 90% probable vertical, horizontal, and 3d spherical radial error, respectively, of an arbitrary geolocation
or geolocation product generated by or using data from the Geolocation System. Order statistics are recommended for their computation based on a recommended minimum number of independent and identically distributed (iid) samples of error, or approximately iid samples of error if certain constraints are met. The underlying probability distribution of errors is neither required nor used. Based on these samples, a best estimate of LE90, CE90, and/or SE90 are computed, as well as corresponding least-upper-bounds computed at a 90% confidence level, in order to assess the accuracy of the Geolocation System and/or determine if corresponding specified requirements are met. Predicted accuracy is associated with an arbitrary but specific geolocation associated with the Geolocation System. It is a “current” geolocation, either already extracted using the Geolocation System’s data, typically via a Weighted Least Squares (WLS) Solution using multiple images, or contained in one of the Geolocation System’s products, such as a Digital Surface Model (DSM). The WLS provides both a best estimate of the geolocation as well as its specific error covariance matrix. Predicted Accuracy is based on predictive statistics, the key statistic is the error covariance matrix uniquely associated with each geolocation, and an assumed type of probability distribution of geolocation errors, typically, either multivariate Gaussian or Laplacian. Using this data, either a 90% probability error ellipsoid (or ellipse) can be computed, and scalar accuracy metrics (LE90, CE90, and SE90) can also be computed that contain less information than the ellipsoid but are convenient summaries.

Predicted accuracy is assessed using (approximately) iid samples of geolocation error normalized by their corresponding error covariance matrices. Results are quantified based on how reliably the error covariance and corresponding probability distribution represent actual geolocation errors. The assessment can also be used to determine if corresponding predicted accuracy requirements for the Geolocation System are met. Reliable predicted accuracy enables informed use of geolocations and/or corresponding products as well as optimal fusion with other geolocation products. This Webinar also presented recommended processing associated with geolocations and their accuracy and/or predicted accuracy, including: (1) specification, assessment, and validation of requirements, (2) computation of error ellipsoids and scalar accuracy metrics, (3) representation of geolocation errors as random vectors, stochastic processes, or random fields, (4) Estimators and their Quality Control, such as WLS batch solutions and Kalman Filter sequential solutions, and (5) Monte-Carlo simulation or errors. Corresponding details are also provided in publicly available and referenced NGA-authored Technical Guidance Documents.

Presenters
John Dolloff, a senior scientist at KBR, has been involved in various aspects of geopositioning for over 40 years supporting the NGA and related organizations as a Subject Matter Expect (SME) specializing in applying advanced linear algebra, estimation theory, probability, and statistics; particularly, as related to photogrammetric principles.

Hank Theiss, a senior scientist who works part-time at KBR, is a Research Associate Professor at the University of Arkansas in the Center for Advanced Spatial Technologies (CAST) with over 25 years of experience supporting NGA and related organizations as a photogrammetry SME.

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