Switch between two images multiple times in a pattern sequence

Claus,

Can you clarify by what you mean when the patterns get distorted? Are they incorrect when projected? Or not the correct bit planes are projected?

If you're able to post screenshots of your GUI and the images you're trying to use, that would be quite helpful.

Thanks!
Paul

Hi Paul
By distorted I mean part of the pattern is projected correctly and part of it is wrong.
When we increase the exposure time the problem goes away, so it seems to be related to the 200ms load time between flash images.
My guess is that the problem is that we switch between the two images multiple times within a sequence. Which means the LightCrafter want to load the first image again, and does not have enough time, because of the 200 ms load time.
If I am correct, what is needed is a way to tell the LightCrafter not to load the first image again, because it should already be buffered.
Regards,
Claus

Thanks for the clarification. Give me a little time to test this out myself. I think you are right about the load timing and I'm wondering what the impact of switching from one buffer to another is, as well as how to tell the Lightcrafter to stop loading data into the buffers when they switch.

I'll post back when I know more. It would be helpful (if you're willing) to post your images so that I can test with your configuration.

Thanks!
Paul

Hi Paul

I have inserted two images for you to test with.

I have used the "Insert File" button, which pasted the images in below. Is there a better way to post the files?

Regards,

Claus

Hi Claus,

I think I understand the issue you are experiencing. I would recommend trying the following solution for optimal performance:

1. Use pattern sequence mode [variable exposure]
   
   
2. When adding your patterns add them in an optimal way to minimize swapping to other side of the buffer, at least the first time
   
   
3. Ensure you allow the 200 ms load time before you access images 3, 4, and 5 (assuming you added them sequentially) by adjusting the pattern period and pattern exposure time 
   
   
4. Once the entire set is loaded in the buffer you should be able to access all of them (decreasing your exposure time), the 25ms (40 Hz) rate you are trying to achieve should not be an issue

In short, once you give it time to load the patterns the first time you should be able to access them safely. 

 

I hope that helps! Let me know if this is unclear or if this fix does not work for you.

 

Best,
~Danny W

Hi Danny

I have tried to simplify the situation a little, so I am just using one pattern from an image0 and another pattern from an image1.

If I create a sequence of 0 1, where the period and exposure time is 25000us, and the patterns are repeated, then the images are displayed correctly.

If I create a sequence of 0 1 0, where the first two patterns have a period and exposure time of 400000us and the last image have a period and exposure time of 25000us and the patterns are repeated, then all the patterns are displayed distorted (part of the patterns are projected correctly and part of them are wrong).

It seems like the problem is, that when the LightCrafter has to switch back to image0, it does not understand that it is already loaded, and hence it starts loading it again.

Regards,

Claus

Hi Claus,

 

Thank you for clarifying. I will try to replicate this issue on my end and and get back to you when I have some additional information.

 

Best,
~Danny W 

Hi Claus,

After doing some digging I found that this is a know issue that can arise when using the same data in one side of the buffer, it has come up before in this thread. Your exact situation is a bit different because you are displaying more bits, but your input has helped narrow down possibles causes. It is something we are looking into.

In the mean time we can try to find a workaround for this. Some possible solutions are:

• Modifying the exposure time to eliminate the corrupt image 
• Arranging the information in your flash images in such a way that it will not reuse the data in this manner
• Adding a duplicate image to the flash so you can call image from a different image it uses the data again

If you have any further information on your specific application that could help me understand how we can incorporate a solution I can take a look at it. 

 

I hope this helps!

~Danny W

Hi Danny

It is not an option for us to modify the exposure time.

We saw the problem when we were trying to implement an improvement, and for the improvement we cannot arrange the patterns in a way, where we don't have to switch back and forth between two images within a sequence.

I don't see that a duplicate image can help in our situation, as it will take too long to load the duplicate image, since we can't change our exposure time.

When the sequence is 0 1 0, the LightCrafter reloads image 0, when it needs to project the third pattern/image. A fix to the problem would be, to be able to tell the LightCrafter, that it doesn't need to load image 0, because it is already loaded. Or that the LightCrafter could automatically figure out that image 0 is already loaded.

Regards,

Claus

Hi Danny

Our limitation is that we have 6 patterns of 8 bits, hence we need 48 bits i.e. 2 images. And we want to display the patterns in an order, which makes it impossible to arrange the patterns in a way, where we can avoid switching between the two images multiple times. Additionally our exposure time is short, which doesn't allow enough time to load any of the images before they are needed.

The interesting part is that the sequence 0 1 works even when repeated, which means the LightCrafter somehow knows that it doesn't need to reload image 0 or image 1, when the sequence repeats.

Regards,

Claus

Hi Claus,

 

Our limitation is that we have 6 patterns of 8 bits, hence we need 48 bits i.e. 2 images. And we want to display the patterns in an order, which makes it impossible to arrange the patterns in a way, where we can avoid switching between the two images multiple times.

 

I do believe I understand your issue. You would like to access the all of the 48 bits in the buffer with out having to reload the images. For the time being the controller reloads the image data when you call on the previously uploaded image again. This a known issue, and is it being looked into. The current recommendation to maximize your pattern display speed is to create images that have your patterns  arranged efficiently as possible. You can also utilize our Image Load Timing estimate tab in the GUI to ensure you are displaying the images as quickly as possible. Some other platforms do have more versatile image display options, I can help recommend alternatives if this is functionality required for your current application. 

 

Best,
~Danny W