June 02, 2015 04:52PM
First, the background: Polygon boundaries, or any lines, are literally straight only if the directions are perfectly north/south or east/west. Any deviation from those directions results in "straight" lines actually being drawn by computers as small zig/zags, the size of which are determined by the default pixel or grid cell size. If the grid cell size of the "zigs" and "zags" is small enough, the lines may appear to be straight to the naked eye.

The problem: I create prescription seeding rate or nitrogen rate applications for on-farm trials. The individual prescription rates are rectangular polygons that usually correspond to planter passes or applicator passes in the field. Field operations are rarely performed in perfect north/south or east/west directions. Consequently, the boundaries of the prescription rate polygons are composed of zig/zags.

The problem I have experienced with exporting prescriptions from Farm Works is that the default grid cell size for the prescription polygon boundaries appears to be 10 to 15 feet or larger. When imported into VR displays, the zigs/zags are very noticeable on the screen (attached image showing colored zig/zags). More importantly, the VR controller believes the zig/zags are really 10 to 15 ft wide or larger. The problem occurs when the VR controller "believes" that more than half of the applicator or planter has crossed over into the adjacent polygon, it will change to the rate of the adjacent polygon. Down the field when the "straight" boundary line zig/zags back the other direction, the rate changes back to what it should be. Not desirable and the problem is worse if the planter or applicator has section controls because then it takes even less of a zig/zag for that section to change to the adjacent rate.

So, what I want to know is whether Farm Works offers an option to change the grid cell or pixel size of the prescription file. I cannot find it if it is there. Ag Leader SMS offers this option when creating prescriptions for Ag Leader displays, though grid cell sizes less than 2.5 ft can bring your computer to its knees due to the memory requirements to generate a gridded layer with such fine resolution.

http://www.agry.purdue.edu/ext/corn/IMG_8689.jpg

RL (Bob) Nielsen
Purdue Univ
W. Lafayette, IN

Farmworks Office v2016.02.00.57
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SubjectAuthorPosted

Pixel / Grid Cell Size for Prescription polygon boundaries

RL (Bob) NielsenJune 02, 2015 04:52PM

Re: Pixel / Grid Cell Size for Prescription polygon boundaries

KathyClineJune 03, 2015 09:51AM

Re: Pixel / Grid Cell Size for Prescription polygon boundaries

RL (Bob) NielsenJune 04, 2015 07:24AM

Re: Pixel / Grid Cell Size for Prescription polygon boundaries

KathyClineJune 04, 2015 08:30AM

Re: Pixel / Grid Cell Size for Prescription polygon boundaries

RL (Bob) NielsenJune 04, 2015 02:10PM



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