Geological image processing of petrographic thin sections using the rotating polarizer stage

One of the fundamental problems with image processing of petrographic thin sections is that the appearance (colour I intensity) of a mineral grain will vary with the orientation of the crystal lattice to the preferred direction of the polarizing filters on a petrographic microscope. This makes it very difficult to determine grain boundaries, grain orientation and mineral species from a single captured image. To overcome this problem, the Rotating Polarizer Stage was used to replace the fixed polarizer and analyzer on a standard petrographic microscope. The Rotating Polarizer Stage rotates the polarizers while the thin section remains stationary, allowing for better data gathering possibilities. Instead of capturing a single image of a thin section, six composite data sets are created by rotating the polarizers through 900 (or 1800 if quartz c-axes measurements need to be taken) in both plane and cross polarized light. The composite data sets can be viewed as separate images and consist of the average intensity image, the maximum intensity image, the minimum intensity image, the maximum position image, the minimum position image and the gradient image. The overall strategy used by the image processing system is to gather the composite data sets, determine the grain boundaries using the gradient image, classify the different mineral species present using the minimum and maximum intensity images and then perform measurements of grain shape and, where possible, partial crystallographic orientation using the maximum intensity and maximum position images.

Canadian Niagara Power Glass Slide - Engineer Drawing of Sections of Discharge Tunnel

Consulting Engineer drawing of Sections of the Discharge Tunnel. Included in the drawing is the "cross section of tunnel with timbering" and "longitudinal section showing Timber in straight tunnel". Dated October 1902.

Estimate of work done on the Port Dalhousie and Thorold Railway by Messrs. Brown and McDonell, contractors, on sections 1, 2, and 3 ending at St. Catharines

Estimate of work done on the Port Dalhousie and Thorold Railway by Messrs. Brown and McDonell, contractors, on sections 1, 2, and 3 ending at St. Catharines for the month of Sept. 1854, signed by S.D. Woodruff, Oct. 1854.

Estimate of work done on the Port Dalhousie and Thorold Railway by Messrs. Brown and McDonell, contractors, on sections 1, 2, and 3 ending at St. Catharines

Estimate of work done on the Port Dalhousie and Thorold Railway by Messrs. Brown and McDonell, contractors, on sections 1, 2, and 3 ending at St. Catharines during the month ending Oct. 31, 1854.

Estimate of work done on the Port Dalhousie and Thorold Railway by Messrs. Brown and McDonell, contractors, on sections 1, 2, and 3 ending at St. Catharines for the month of Oct. 1854

Estimate of work done on the Port Dalhousie and Thorold Railway by Messrs. Brown and McDonell, contractors, on sections 1, 2, and 3 ending at St. Catharines for the month of Oct. 1854, signed by S.D. Woodruff, Nov. 1854.

Chart of estimate of work done on the Port Dalhousie and Thorold Railway by Messrs. Brown and McDonell, contractors, on sections 1, 2, and 3 ending at St. Catharines for the month ending Dec. 1, 1854

Chart of estimate of work done on the Port Dalhousie and Thorold Railway by Messrs. Brown and McDonell, contractors, on sections 1, 2, and 3 ending at St. Catharines for the month ending Dec. 1, 1854, signed by S.D. Woodruff, Jan. 1855.

An estimate of work done by Messrs. Brown and McDonell, contractors on sections 1, 2 and 3 ending at St. Catharines for the months of April and May 1855

Scrap of paper that has been burned almost completely. Only the header of the document is intact. It is an estimate of work done by Messrs. Brown and McDonell, contractors on sections 1, 2 and 3 ending at St. Catharines for the months of April and May 1855.

Chart of estimate of work done on the Port Dalhousie and Thorold Railway by Messrs. Brown and McDonell, contractors, on sections 1, 2, and 3 ending at St. Catharines

Chart of estimate of work done on the Port Dalhousie and Thorold Railway by Messrs. Brown and McDonell, contractors, on sections 1, 2, and 3 ending at St. Catharines for the month of Oct., 1855. This document is water damaged and full of holes. The list of prices is almost completely illegible. The document is signed by S.D. Woodruff, Nov. 1855.

Schedule of prices for Brown and McDonell, contractors, for sections 1, 2 and 3 of the Port Dalhousie Thorold Railway

Schedule of prices for Brown and McDonell, contractors, for sections 1, 2 and 3 of the Port Dalhousie Thorold Railway (1 page, handwritten), Sept. 24, 1856.

Diagrams of cross sections on the Welland Railway, Port Dalhousie

Diagrams of cross sections on the Welland Railway, Port Dalhousie (4 hand-drawn diagrams), March 1860.

Cross sections of excavation required to make a ditch on the earth side of the railroad near Port Dalhousie

Cross sections of excavation required to make a ditch on the earth side of the railroad near Port Dalhousie. This is a 12 page booklet of hand- drawn charts and diagrams which is slightly stained. Text is not affected, Mar. 1860.