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65 lines
3.1 KiB
Markdown
65 lines
3.1 KiB
Markdown
# Reference Image
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!!! Note
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The Reference Image is the basis for the coordinate system of the ROIs. Therefore it is very important, to have a well aligned image, that is not rotated.
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At first an example image is shown.
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To define a new reference image push the button `"Create new Reference" (2)` and afterwards `"Take Image" (2)`. It might take some seconds for processing, then your actual camera image should be shown.
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Then play with the provided parameters to get a good result.
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{: style="width:500px"}
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## Focus
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This is the first time, where you have access to the camera image. It most likely is out of focus and not sharp!
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Ensure a sharp image of the camera by adjusting the focal length of the ESP OV2640 camera.
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!!! Note
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Try to adjust the focus for the clearest possible image!
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In order to use it for reading a meter, the focal-length of the OV2640 camera has to be manipulated.
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By default it only results in sharp image for distance bigger than around `~40cm` which is not ideal for our purpose.
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Therefore you need to remove the fixing glue of the OV2640 lens with a sharp knife. After this you can rotate the lens in and out. Rotating it by about a quarter of a turn counterclockwise results in a focus plane shift of about 10cm. You need to figure out your best setting with a little bit of trial and error for your specific environment.
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!!! Error
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Be **very** carefully when rotating the lens. Best is to held the camera itself with one hand or a plier and rotate the lens with the other hand.
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Make sure **not** to rotate the whole camera as this can damage the ribbon cable!
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!!! Warning
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This modification will void any warranty, as the sealing of the lens objective is broken!
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!!! Warning
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This modification will render the camera unsuitable for general, web-cam type applications unless the focal length is changed back to the original setting.
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## Correct Horizontal Alignment
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Ensure an **exact horizontal alignment** of the number:
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| :heavy_check_mark: Okay | :x: Not Okay |
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| --------------------------- | ------------------------------- |
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!!! Warning
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Updating the reference image also means that all alignment images and ROIs needs to be configured again.
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Therefore do this step later only with caution.
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If everything is done, you can save the result with `"Update Reference Image" (4)`.
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!!! Note
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A reboot is not required at this point of time.
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As next you should update the [Alignment References](Alignment.md).
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## Dealing with Reflections
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Reflections can be caused by the flash LED and make it hard to provide a reliable detection.
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There are various ways to deal with them:
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- Attach a diffusor in front of the LED, eg. a filt (Filz) or parchment paper. Also white paper can do the job.
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- Rotate the ESP-CAM so the LED is on another place.
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- Reduce the LED intensity.
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- Use external LED stripes, eg `WS2812x`.
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