I want to measure the width along the green line in the image, I applied filters like canny via OpenCV but I guess the filter didn't work (can't show the edges) because of the very high temperature. My idea is to draw 2 vertical lines and measure by drawing a line between them (I want to draw the vertical edges of the object in the picture, so). Is there any method that can work for this?
The red component binarizes wonderfully, so it won't be a big deal to find the sides.
For more accuracy, you can lowpass filter vertically to reduce noise. You can also do subpixel interpolation by using a linear model that straddles the edge. But I am not sure that this luxury is required for your case.
Lowpassed: