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DLPLCR4500EVM: DLP to achieve high-speed projection using Video port.

Gopi Raju Matta
Prodigy 175 points
Part Number: DLPLCR4500EVM

Hello,

My application is high-speed 3D reconstruction using structured light system. Here I am doing line scanning for the same. I want to make use of maximum available speed, which is 4225Hz.

Available options:

1) Store the patterns in flash memory and achieve this speed. As suggested by manual, only 48 bit planes can be saved in buffers. But line scanning need 912 bit planes(number of columns of projector). So it is not possible to achieve the required speed using this.

2)Use video port and achieve 2880Hz. Here my question is once I use video port, it is again limited by my laptop screen refresh rate which is 60Hz as whatever shown on the screen is being projected. In the manual also it is not so clear to me how to use video port to achieve 2880Hz. Do we need to use GUI for this?

If any other possible option to achieve this, please do suggest.

I went through threads related to it. But not so clear to me.

Kindly please guide me through.

Thank you
Gopi

  • 0
    TI__Mastermind 20045 points

    Hello Gopi,

    If you need more than the 48 pre-loaded patterns you will need to use external input. As you mentioned this will be limited to 2880Hz. If you can only input 24-bit depth 60Hz video you will be limited to 60 Hz * 24 bit depth = 1440 Hz single bit depth display. You may need a different graphics card or an FPGA if you are unable to achieve a higher external input frame rate.In any case, the GUI is to setup your bit plane display. The way you input video is independent of the GUI.

    Thanks,

    Kyle

  • 0 in reply to Kyle Rakos
    Prodigy 175 points

    Thank you so much Kyle for very apt answer.

    I have some follow up questions.

    1) In my application I want to use single bit depth patterns which are lines. If I combine 24 lines into 24 bit planes and then send it then DLP considers it as color image and displays accordingly as mentioned in $4.1 of the manual. But I don't want this kind of projection. I want to assign equal time for every bit depth plane. How can I achieve this?

    2)If I send every bit plane separately by considering it as 24 bit depth then I can only send 60 lines which limits my speed of application.

    Kindly please suggest possible solution.

    Thank you

    Gopi

  • 0 in reply to Gopi Raju Matta
    TI__Mastermind 20045 points

    Hello Gopi,

    This can be accomplished through the GUI as shown below for three patterns (simple extend it to as many as you have in a frame - i.e. 24 for you). You can set equal time per pattern.

    Thanks,

    Kyle

  • 0 in reply to Kyle Rakos
    Prodigy 175 points

    Thank you so much Kyle.

    As you suggested I am combining 24 sequential lines into one 24bit RGB image by considering each line as 1-bit plane. Like that I am creating 912(number of columns)/24 images and then created video with 60 frames(max. refresh rate supported by my laptop) per second. Then I created 24 bit planes as given and pressed send and then validate the sequence.

    Is it the same that you suggested? If I am wrong, kindly correct.

    When I started playing the video, I pressed play button in GUI. It is working but there is flickering and output is not that we expected.  One more problem I am facing is: manual suggests that we should have same resolution(912x1140) while playing. But my laptop doesn't have that resolution. May be this is one of the issues that is causing these undesired effects, while playing the video.

    Kindly provide possible solution.

    Thank you

    Gopi

  • 0 in reply to Gopi Raju Matta
    TI__Mastermind 20045 points

    Hello Gopi,

    It sounds like what you are doing is correct. Unfortunately you need exactly 912x1140 resolution to use this mode. There may be software that can change this on your computer. But if not you may need an alternative front end (different graphics card or FPGA).


    Thanks,

    Kyle 

  • 0 in reply to Kyle Rakos
    Prodigy 175 points

    Hello Kyle,

    Thank you for all your support. I was little off from this.

    I have difficulty in getting same resolution as that of projector nation resolution. I've got a new idea to get it done.

    I want to use same idea for the RGB images to store in flash memory. Section 4.1, page number 43 paragraph-2 tells that "For other applications where this image enhancement is not desired, the video processing algorithms can be by passed and replaced with a specific set of bit-planes." If I am able to bypass it, I can store my patterns as you suggested. So each RGB image can project 24 lines. So in flash memory as I can store up to 64 images, it will do my job.

    But I couldn't find any information about how to bypass. Kindly please guide me through this.

    Thank you

    Gopi

  • 0 in reply to Gopi Raju Matta
    Prodigy 175 points

    Oh, I am little confused.

    This one also won't solve my problem as only 48 bit planes can be projected at the same speed. Two load next 24 bit planes it will take .2s as per manual. I am sorry for that.

    Anyhow please guide me how to bypass the same to achieve the highest speed to project binary patterns, which might be 10 in number(less than 48).

    And also I tried with software like Custom Resolution Utility to adjust custom resolution. The desired resolution is added into the set of resolutions. But when I am trying to apply it, it is failing. Can you please suggest any other solution?

    One of my other doubts is that is that native resolution 912x1140 or 1140x912. Because when I see the projected images I am seeing it as reverse.

    Thank you

    Gopi

  • 0 in reply to Gopi Raju Matta
    Prodigy 175 points

    Gentle reminder of the same.

    Thank you

    Gopi

  • 0 in reply to Gopi Raju Matta
    TI__Mastermind 28005 points

    Gopi,

    If possible, you should try examining the EDID of the system as reported by your OS before you start tuning with custom resolution utility. What "failing" behavior do you encounter when applying a custom resolution with CRU?

    Regards,

    Philippe Dollo

  • 0 in reply to Philippe Dollo
    Prodigy 175 points

    Thank you so much for your reply Philippe Dollo,

    My screen maximum resolution is 1920*1080. DLP needs resolution 912*1140. So number of rows of DLP are greater than that of my screen. This might be the reason, I am not very sure. When I tried with 1140*912 CRU worked.

    I am not sure of EDID of the system. If it solves my problem, I will surely look into. Please provide little more insight on this. Does DLP video work with any other resolution? Kindly suggest needful.

    Thank you

    Gopi

  • 0 in reply to Gopi Raju Matta
    TI__Mastermind 20045 points

    Hello Gopi,

    Philip is correct for external video it will be important to exactly match resolution and updating the EDID may be one way to do this. However, it is possible your graphics card still wouldn't support 912 x 1140 video. 

    When using internal pattern sequences configured from the GUI you are bypassing the image enhancement functions. I believe that was your question concerning the internal pattern mode. For additional related questions please feel free to open a new thread  if needed.

    Thanks,

    Kyle

  • 0 in reply to Kyle Rakos
    Prodigy 175 points

    Thank you Kyle. Your information is very useful.

    I will try updating the EDID. Anyhow CRU should work right, if my graphics card support the needed resolution. My graphics card is NVIDIA 940mx. We purchased pandaboard also but couldn't make it work. Is there any simple guidelines that I can follow to integrate LightCrafter with pandaboard? Please refer if any. I got some but I couldn't follow.

    Concerning bypassing image enhancement mode, I got it exactly that you answered. I could do that.

    Coming to pattern sequence mode, if I have 10 patterns need to be projected, I need to do the same for each bit plane that is total 24*10=240 bit planes. Is there any easy way to repeat the same settings for pattern like that of external video?

    Once we set the pattern sequence settings, can we store the same into firmware? Then we no need to do the same again and again.

  • 0 in reply to Gopi Raju Matta
    TI__Mastermind 20045 points

    Hi Gopi,

    Using a bypass to ignore the EDID like CRU should theoretically work. I am not sure on the specifics of your graphics card but please try. I think there is some information using the Pandaboard in the DLP4500EVM user's guide; however, I don't know if the Pandaboard is officially supported anymore. 

    The GUI is the official way to create the patterns. We also have an SDK; however, this is no longer officially supported. 

    Thanks,

    Kyle

  • 0 in reply to Kyle Rakos
    Prodigy 175 points

    Thank you Kyle. I will check out these things and get back to you.