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Author Archives: joelgranados
R : Finding the ordering index vector
The ordering index vector is a vector that contains indices of another vector. It’s basically the other vector, but ordered (decreasing or increasing). Instead of having the values it has the indices :) I spent close to an hour to … Continue reading
Posted in commands, R
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Curious rounding in R
Sometimes R has a misleading way of displaying values. Check out this series of commands: > 1111+.5 [1] 1111.5 > 11111+.5 [1] 11111.5 > 111111+.5 [1] 111111.5 > 1111111+.5 [1] 1111112 > 11111111+.5 [1] 11111112 At first I thought that … Continue reading
Posted in commands, PhD, R
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Adjusting point size in R plots.
The trick here is to manage the pch and cex arguments in the plot function. You can look at more information on these arguments in ?plot, ?par and ?points in the R environment (search for cex and pch). In general … Continue reading
Posted in commands, R
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How to output an eps figure in R
If you are executing a plot command in a R script it should default to generating a pdf document with your plot. This is really cool because you don’t really have to think about how to show what you have … Continue reading
Posted in commands, PhD, R
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About opencv cornerSubPix
There were some issues with some of the classification tests I ran on the chessboard pictures from last week (you can find pictures here). The ones that were taken from a distance of a couple of meters or less, classified … Continue reading
Posted in opencv, PhD
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Image labeling is taking shape.
After discovering that the accuracy of the chessboard detection is increased by adding a black frame around the chessboard, I went on to create a python library based on what I already had. I created a python/C++ interface and some … Continue reading
Posted in opencv, PhD
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Paper: Fault Tolerance in Autonomous Systems: How and How Much?
Possible research for fault tolerance and robustness in autonomous systems: Agent based architecture: Though a three tier architecture is predominant in autonomous embedded systems, the agent approach could work because of 1.Avoiding semantic mismatch given that all agents have the … Continue reading
Posted in papers, PhD
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Chessboard format
It’s reasonable to describe the chessboard format. It’s relevant because not all chessboard dimensions are valid, The current implementation only detects 6 colors and there needs to be a black margin around the chessboard (among other reasons). Chessboard dimensions: We … Continue reading
Posted in opencv, PhD
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Unexpected solution to a detection problem
Before leaving for vacations I was fighting a very curious issue with my chessboard detection algorithm. All my tests were done with pictures of chessboards that occupied most of the image. The tests where very positive even for outside picture … Continue reading
Posted in opencv, PhD
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Back from paradise.
Today is my first day in the office since my long Colombian holidays. I need not stress how awesome it was to go back to my home town and share experiences with my past :) Today (besides trying to overcome … Continue reading
Posted in Uncategorized
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