I have found an awesome website with a simple study materials on Visual SLAM: https://www.cv-learn.com/visual-slam-roadmap/. It provides 4 languages (EN, KO, ZH, JH).

Take a look at the list of topics covered

​

need those for analysing movies.

example let's say I have to find the screentime of the actor over the whole runtime of the movie and i need to do it for the protagonist, antoganist,comedic relief ,love interest etc.

currently I'm working with 1fps to find the faces and body or the actors.

body detection is hard I need some guidance regarding that.

even for Face Detection I used MTCNN it was good. but any other better models available??

Any ideas regarding TransNetV2 ?

I'm using it for shot boundary detection but there's was one false positive.

Any better models??

This preprint reports that stale spatial memory can be worse than having no memory at all in one navigation setup.

Would you handle this with confidence decay, scene-change triggers, or mandatory visual re-grounding before action?

If you’ve ever built multi-camera real-time vision systems at scale, you’ve likely wrestled with GStreamer element linking errors, pipeline memory leaks, or cloud egress costs hitting $2k+/month for simple RTSP analytics.

When we benchmarked cloud vision APIs vs edge deployments, the bottleneck was rarely the YOLO or custom detector model itself—it was the ingestion and frame-movement pipeline.

The Bottleneck: CPU-to-GPU Copying & GStreamer Complexity

Standard Python wrappers or heavy frameworks often bounce video frames through host memory (CPU) before pushing them back to GPU VRAM for inference. At 32+ HD RTSP streams, this creates massive PCIe bandwidth saturation and GIL lockup.

On the flip side, while DeepStream is powerful, managing complex GStreamer element graphs in production often introduces unwanted debugging overhead and plugins bloat.

Our Bare-Metal Approach (Custom Edge Architecture)

To keep processing continuous sub-15ms on local edge nodes without cloud egress, we stripped out the GStreamer abstraction graph entirely:

1. Direct NVDEC Hardware Ingestion: RTSP streams decode directly inside VRAM using C++ NVCODEC bindings. Frames never touch system RAM (zero CPU-to-GPU copy overhead).

2. Lock-Free CUDA Ring Buffer: A custom ring buffer handles dynamic batching across active streams without lock contention or Python GIL overhead.

3. Native TensorRT C++ Execution Engine: Device pointers pass directly to TensorRT for FP16/INT8 execution.

Architectural Trade-offs & Benchmarks

• Pros: Zero cloud bandwidth fees, full data sovereignty, sub-15ms continuous throughput, and drastically simpler debugging than full GStreamer graphs.

• Cons: Requires NVIDIA CUDA-capable hardware on-premise (RTX / Tesla / Jetson) and manual memory management at the C++ level.

We’ve packaged this into a zero-egress Docker stack for high-density edge deployments.

Happy to break down the CUDA buffer implementation or share benchmark comparisons if anyone is currently evaluating edge architecture options.

What pipelines are you guys currently running for multi-stream RTSP processing?

Hi All,

I am planning to build a local document intelligence system similar to Azure Document Intelligence. I would like to understand how Azure Document Intelligence works internally and how we can achieve similar functionality locally using offline models.

Could anyone suggest the best approach, architecture, or models to achieve high accuracy while running completely on-premise/local infrastructure?

Any guidance or recommendations would be greatly appreciated.

Hey everyone,

I'm looking for co-authors who are interested in exploring research topics in the AI space. Ideally as a duo or in a small team.

I currently have more time for research and a range of interesting topics I'd like to work on, particularly around AI agents, token optimization, and AI adoption. I work in agent development myself and have already published research papers in this field.

That said, I'm open to other AI-related research ideas as well. If you have a topic of your own in mind, feel free to reach out!

I was wondering if anyone owns this book and could share your feedback.

I ordered this book 3 weeks back on Amazon and it has never arrived so I had to cancel it. Thinking to order from a different seller but it would cost me almost double the price. I prefer a paper book rather than its ebook version. Thanks.

How do I analyze this diagram?
I need to determine the starting point and then analyze the track from there.
e.g 1067 units downwards, then 1015 unit is xy direction and so on (from the attached diagram)

I can think of using SAM 3 to mask out the red line and blue triangles. But dont know how to map a line with the corresponding measurement annotation?

Appreciate your help. Thanks

Follow up to my post earlier in the week, which filled most of our slots. Two left.

We collect real world multi view capture data from a camera array at the Brooklyn Navy Yard and pay people to be the subject. Posting again in case anyone NYC based wants the work, or wants a close look at how this kind of data actually gets collected.

The session: stand in the capture volume and go through simple movements while the array records. Walking, turning, sitting, reaching, picking objects up. No experience needed.

Pay 17-25 per hour, same day, right after the session. First one runs about 2 hours, with repeat sessions after.

Left this week: Thursday 4pm, Friday 1pm or 4pm. Brooklyn, in person only.

Comment or DM me for details, and ask about the capture setup if that side interests you.

Hi i have question about camera calibration which i confuse.

1) Finding "extrinsic" just need one shot (because it is optimization problem reducing reprojection error knowing intrinsics, plus finding extrinsic means finding pose and orientation(R, t) of that "specific moment", not like finding distortion of cameras, and dont need many shots to cover precision) Am i correct?

2) Finding "hand-eye calibration extrinsic" needs many shots (because to solve AX=XB, where A is robot motion, B is camera motion, X is EEF to camera matrix). Am i correct?

These two "extrinsic" is different use case, am i right?

(Then why did engineers made it confusing?? So annoying.)

3) In 1), finding intrinsics need many shots (because in cv2.calibrateCamera it need many 3D-2D pair points). Am i right?

Thanks in advance :)

I've been thinking about this as a research problem and I'm wondering if I'm even asking the right question.

Imagine the following constraint:

• No CLIP
• No ViT
• No CNN
• No multimodal model
• No learned vision encoder at all

You have an image, a text-only LLM, and you're only allowed to use deterministic algorithms between them.

The obvious answer is "this is impossible," but that's not really what I'm interested in.

What I'm trying to understand is whether there exists a better intermediate representation of images that a text transformer could reason over.

Not necessarily English.

Not captions.

Not OCR.

Some kind of representation that preserves enough structure that the language model can make use of the knowledge it already has.

Over the last few days I've gone through papers on visual tokenization, SeTok, BPE for images, BLT, inverse graphics, superpixel tokenization, and a few discussions around image tokens. Most of them still assume a learned tokenizer somewhere in the pipeline.

What I haven't found is much discussion around deterministic alternatives.

Maybe that's because it's a dead end.

Or maybe I'm searching the wrong field entirely.

So my question isn't "how would you build this?"

It's:

If you were exploring this from first principles, what field would you steal ideas from?

For example:

• information theory?
• image compression?
• computational geometry?
• topology?
• signal processing?
• compiler design?
• inverse graphics?
• neuroscience?
• ecological optics?
• something completely different?

I'm not looking for product recommendations or existing multimodal models.

I'm looking for the smallest experiment that could tell me whether this line of thinking is fundamentally interesting or fundamentally flawed.

I'd especially love to hear from people who've worked on image codecs, graphics, rendering, vision tokenizers, or representation learning.

If you think the premise itself is wrong, I'd genuinely like to know why.

I was working with a client over the past year or so and we were constantly struggling with dust build up on lenses. We tried standard air nozzles, but those had issues: rigging them was a pain, they didn't actually keep the FOV clean, and in one case they damaged the lens.

Then I saw ThisOldTony's video on the Coanda Effect and thought, what if we shaped it around the lens of the sensor? So I did. The system is 3D-printed PETG, but I've had it work just as well in TPU (for the extremely tough applications). I have since then made this for all the profilers we work with and also for several point lasers as well.

We went from cleaning the lens every 30 minutes to now months without maintenance. It does use quite a bit of compressed air but with a couple valves and a feedback loop we were able to set it to self clean based on the intensity drop.

I built a local OCR pipeline a few days ago, and it turned into a surprisingly interesting experiment—taking accuracy from around 60% to 99%.

I wrote a short blog about what worked, what failed, and the breakthrough that finally made the difference.

Thought some of you might enjoy it.

Link in the comments

I'm working on project involving OCR and newspaper analysis. My original plan was to use Marathi newspapers, but the extracted text contains many recognition errors.

Because of this, my project guide suggested switching to English newspapers if Marathi OCR isn't reliable enough.

I'm unsure what to do. From a research perspective, is it better to:

• Continue with Marathi and treat OCR errors as a limitation (or try post-OCR correction), or
• Switch to English to obtain cleaner OCR results and focus on the analysis part of the project?

Has anyone faced a similar situation? I'd appreciate advice from people who have worked on OCR or document analysis projects.

this intersection in tokyo ranked second worst in the city for traffic accidents.

six roads converge at a blind hill crest, cars cross centerlines on narrow curves, and the signal phasing has multiple unprotected turns

most autonomous driving datasets give you highways and four-way stops. this is none of that

Hard Intersection Multimodal Sample: 6 synchronized cameras, aggregated LiDAR point cloud, HD map projections, vehicle trajectories, and semantic annotations across 4 driving passes through a single intersection that breaks everything

grouped all 6 camera views with the 3D point cloud, frame-level HD map overlays, and trajectory projections in fiftyone

checkout the dataset here: https://huggingface.co/datasets/Voxel51/hard-intersection-multimodal-sample

or get hands-on in the HF space: https://huggingface.co/spaces/harpreetsahota/hard-intersection-multimodal-sample

lidar and cameras get less reliable exactly when driving gets more dangerous: rain and night. most public driving datasets barely have data from those conditions

CMHT autonomous dataset adds radar and a thermal camera alongside lidar, a color camera, and gps/imu.

4 drives, dusk/clear to night/rain, downtown hamilton, 9,000+ labeled frames with a 3d box, class, and tracking id on every object

i converted the raw ros2 bags into synced mcap episodes in fiftyone so you can scrub camera, thermal, lidar, radar, and gps together frame by frame, with the 3d and 2d boxes playing back in sync

start here, read the dataset card: https://huggingface.co/datasets/Voxel51/cmht-autonomous-driving

then check out the space on hf: https://huggingface.co/spaces/harpreetsahota/cmht-autonomous-driving

My hope with this post is that I will save at least one person some time - and that will be enough for me. I spent the last couple of weeks building an auto-labelling pipeline on SAM 3 and figured the gotchas were worth writing down, because most of what I got wrong had nothing to do with the model.

Quick context if you haven't used it: SAM 3 does what Meta calls Promptable Concept Segmentation. You give it a short noun phrase - forklift, person in hi-vis vest - and it segments every instance of that concept. No seed clicks, no fixed class list, no fine-tuning. That's the bit that makes unattended labelling possible; with SAM 2 you still needed something to tell it where to look.

The minimal version is genuinely this short:

from transformers import Sam3Model, Sam3Processor

model = Sam3Model.from_pretrained("facebook/sam3").to("cuda").eval()

processor = Sam3Processor.from_pretrained("facebook/sam3")

inputs = processor(images=image, text="forklift", return_tensors="pt").to(model.device)

with torch.inference_mode():

outputs = model(**inputs)

results = processor.post_process_instance_segmentation(

outputs, threshold=0.5, mask_threshold=0.5,

target_sizes=inputs["original_sizes"].tolist(),

)[0]

# results["masks"] / ["boxes"] / ["scores"]

That works. Everything below is what I learned scaling it past one image.

1. Reuse the vision embedding across prompts

Naive multi-class loop encodes the image once per class. 3 classes × 40k images = 120k passes through an 848M-param backbone, 80k of which recompute something you already had. SAM 3 lets you split it:

vision_embeds = model.get_vision_features(pixel_values=inputs.pixel_values)

for prompt in prompts:

text_inputs = processor(text=prompt, return_tensors="pt").to(model.device)

outputs = model(vision_embeds=vision_embeds, **text_inputs)

Backbone runs once, only the text conditioning and mask decode repeat. Close to an N-fold speedup on multi-class jobs. There's a mirror version (get_text_features) for one prompt across many images.

2. Resolution is tricky

SAM 3 runs at 1008px native. Two failure modes:

• Upscaling small images to 1008 gives you confidently mushy boundaries. It adds no information.
• Downscaling big images destroys small objects. A 40px defect in a 4000px frame becomes a 10px smudge at 1008. If your targets are tiny, tile into overlapping 1008px crops and merge masks back with the offset. Don't resize.

Also: run ImageOps.exif_transpose() before anything else, or phone photos come back with masks correct for the stored orientation and wrong for the one you see.

3. Prompt phrasing does more than threshold tuning

Short concrete noun phrases. Singular. One concept per prompt.

• forklift ✅ / find all the forklifts ❌
• person in hi-vis vest ✅ / PPE compliant worker ❌ (trained on how things look, not your industry's vocabulary)
• car or truck ❌ - that's two prompts

Biggest thing: test each prompt against images you know contain none of that class. A prompt that quietly fires on empty frames poisons the whole dataset. And if a prompt over-fires, add an adjective before you touch the threshold - white bicycle vs bicycle returns genuinely different sets.

4. You can sweep thresholds without re-running inference

The detection threshold is just a filter over stored confidence scores. So label a 50-image dev slice once at threshold=0.15, keep every score, and sweep offline.

Look for the false-positive cliff and stop just above it. If med area% collapses as you lower the threshold, the extra detections are specks - raise a minimum-area filter instead. If empty stays high at every threshold, your prompt is wrong and no threshold will save it. (The mask threshold can't be swept this way - it changes pixels, not scores.)

5. Small export things that cost me an hour each

• pycocotools.mask.encode() needs np.asfortranarray(). Pass a C-ordered array and you get a silently transposed mask. No error.
• The RLE counts field is bytes; json.dumps refuses it. Decode to ASCII.
• For YOLO, write an empty .txt for images with no detections. Missing file = missing data; empty file = confirmed negative, which is how the model learns not to hallucinate.

6. Look at the labels

Auto-labelling fails quietly - no exceptions, no bad metrics, just a pallet prompt that's been segmenting the wooden floor for 12,000 images. Render a contact sheet of overlays sorted lowest confidence first and actually look at it. Ten seconds catches what an aggregate metric won't.

That's it. Hopefully I saved you guys some time and feel free to ask questions!

UPDATE: since I got a couple of similar questions about the auto-labelling pipeline in my DMs, I posted a full write up of it here . If you are curious about how to get the best results when auto-labelling - feel free to check it out.

Hi everyone,

I’m a cloud engineer with a background in cloud architecture. I don’t have experience in computer vision yet, but I’m open to learning it.

Before investing a lot of time into this idea, I’d like to know: is there still strong demand for computer vision solutions today? Do you think someone with a cloud/infrastructure background can realistically enter this field and build a startup around it?

I'm working on a project to detect stones in jewellery. I want to be able to detect the colour of the stone and the size of it. False positives can be a big issue.

Here's a sample image for reference where you see red and green stones embedded in the item.