# Tag Info

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### What does Simultaneous Localization And Mapping (SLAM) software do?

Localization is the process of estimating the pose of the robot the environment. Number 5 in your list. Mapping is estimating the position of features in the environment. Number 1. 2, 3, and 4 are ...
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### SLAM: Why use two cameras (stereo) if SLAM can be done using single camera (monocular)?

The most important point is the scale. If you do monocular SLAM, your map will only be accurate up to scale so that you e.g. cannot compute the length of the travelled path in meters. The scale ...
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### Understanding Drift in Simultaneous Localization and Mapping (SLAM)

Your intuition is mostly correct. Returning to where you started and re-observing landmarks you mapped earlier is called closing the loop in the SLAM literature. As you mentioned, your uncertainty ...
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### Difference between SLAM and "3D reconstruction"?

You are right about the sameness of SLAM and 3D reconstruction. At the same time I don't think the author is misclassifying. The english is a little non-standard. The author could have better said it ...
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### Which is a good and cheap 3D LIDAR or other options?

There are now some sub and around ~1000USD 3D Lidars available. I wanted to provide an answer for future reference if anyone else comes looking for "cheap" Lidars. LeddarTech M16 ~500 USD ...
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### In SLAM loop closure, What does a sim3 matrix do?

Sim3 is just the lie group associated a similarity transform which is the exact same thing as your 3D Affine transform. If you work out the multiplication for your two matrices you would find that ...
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### What's the difference between Pose Measurement and Position Measurement?

what you are looking for is written in the paper. Position refers only to x,y,z translational measurements while pose means position and orientation.
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### SLAM : Why is marginalization the same as schur's complement?

The following are mostly based on "Factor Graphs for Robot Perception" by Frank Dellaert and Michael Kaess, with additional notes: As a reminder, marginalization is about having a joint ...
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### Are there any advantages to using a LIDAR for SLAM vs a standard RGB camera?

My question: are there cases where you'd still need a LIDAR or can this expensive sensor be replaced with a standard camera? ... A each one of them has its advantages/disadvantages. Thus in some ...
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### Multiple View Triangulation method used by COLMAP

This method is minimizing the reprojection error of the triangulated point. How to see this: Let $P_i$ be the $3 \times 4$ projection matrices, and let $x_i \in \mathbb{R}^3$ be the (homogenized ...

### Difference between SLAM and Localization

Localization is always done with respect to a map. SLAM(Simultaneous Localization and Mapping). As it is in the name, also does localization with respect to a map. The only difference is that the ...
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### What is the Point of Monocular SLAM

I would say true scale actually doesn't really matter. A good way to reason about this is actually video games. If you play a racing game(or really any kind of 3D game) do you care that the world has ...
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### Marginalization vs Dropping states for sliding window VO

Short answer: Marginalization is a fancy way of applying a prior on certain nodes of your factor graph. Note that Marginalization vs Dropping data is not only specific to the sliding window case, but ...
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### Pose-Graph-SLAM: How to create edges if only IMU-odometry is given?

First off, it doesn't sound like you're actually doing SLAM. You didn't mention an exteroceptive sensor (e.g., laser, camera) that actually maps the environment. With just an IMU, you are doing ...
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### What's the difference between the term "pose estimation" and "visual odometry"?

It is also often the case that the author lacks knowledge, makes mistakes, or is adding unnecessary statements to their work. Just because it is published does not make it true. In this case though, ...
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### What's the difference between the term "pose estimation" and "visual odometry"?

Pose estimation means determining position and orientation. Odometry is using a (any) sensor to determine how much distance has been traversed, so visual odometry is just clarification that the ...
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### Suggestion for relevant non-complex simulator

just use matlab or and python with a set of fixed features in space represented as points. Don't do any vision processing. At this point any vision processing would be overkill. you are making this ...
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### How does fast slam creates grid maps?

Grid based FastSlam relies on the same principle that Landmakr based FastSlam. The difference is that we are not working with each grid cell as a landmark, but the whole gridmap itself. For Grid ...
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### Integrating GPS into Graph SLAM (how orientation fixed?)

You can use a very low information matrix value at the orientation elements of your state, given that the information matrix is the inverse of the covariance matrix. The covariance matrix ...

### 3D mapping using only a 2D Lidar

That is an already solved problem. As Squelsh mentioned CSIRO released its initial version in 2009 and their work is commercialized by GEOSLAM already. One of a CMU student released a open source ...
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### Why do we need a marginalization in Bundle Adjustment?

I am still not entirely sure what you are asking, but I believe this may answer your question. Also note I myself don't fully understand all the details behind the marginalization trick, but I will ...
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### Occupancy grid maps

As the wikipedia page of Occupancy grid mapping explains, the result of the mapping process is a binary 1 or 0, occupied or not, the decision itself may be based on noisy data, which involves the ...
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### Calculate transform from different poses

I am just going to explain from the basics. So feel free to skip through the first part and scroll to the bottom if you want the answer. Basics: The 3 parameters of your pose are $x,y,\theta$. These ...
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### Some doubts regarding SLAM and its technical terms

Q1) Online SLAM vs Offline SLAM. Can "Online" SLAM be also called "real-time" SLAM? What is the use of offline SLAM if it can't be used on a real robot in real-time? Yes, online ...
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### Why have EKF and PF slam algorithms been abandoned?

Particle filters while not abandoned have become quite rare. Nowadays they are really only used to solve localization problems. The reason being that they are quite expensive (each particle ...
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### Why do we need to know the translation between Camera and IMU?

You answered yourself. Your underlying model of point moving through space usually assumes the center of gravity to match the camera frame. If your inertial sensor have a translational offset from ...
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### Autonomous Mapping help!

I think there is a bit of misconception with what SLAM does, just remember that SLAM stands for; Simultaneous Localization and Mapping, what you want is to explore the map (autonomously of course) so ...

### What does Simultaneous Localization And Mapping (SLAM) software do?

Which software? Yes, It creates map from its starting point. And robot locates itself in its generated map when generating map. It is using laser data to locate robot in map, when process starts, map'...