# Questions tagged [occupancygrid]

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### Pre-computation of likelihood field

In Thrun's Probabilistic Robotics, section 6.4 "Likelihood Fields for Range Finders", there's mention of pre-computing the likelihood field in practice, for the sake of computational ...
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1 answer
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### Minimize Waypoints Why Still Maintaining Distance From Objects for Motion Planning?

I'm working on a project where I want to give instruction to blindfolded participants on how to walk around an obstacle course. I'll map out my room and convert it to a grid map. However, given that I ...
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### offset in gridmap

colleagues, i am currently viewing Cyrill Stachniss's course on SLAM and also doing the exercises. At the moment i am doing an exercise on occupancy grid mapping and there is some strange offset ...
1 vote
1 answer
31 views

### Uniform and non-uniform cost maps [closed]

I can not find a clear answer on the internet about the difference between a uniform and non-uniform cost map. I am interested in getting an answer in the context of grid maps for robot navigation. ...
1 vote
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### Set global_frame and robot_base_frame parameters for costmap_2d::Costmap2DROS object

I am trying to use a costmap_2d::Costmap2DROS object to read the occupacy grid being published on the /map topic. How do I ...
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1 vote
0 answers
129 views

### Sensor model and Inverse sensor model using occupancy grid mapping with lidar for particle filter

I'm a bit confused about how one goes about calculating the sensor model $p(z_t|x_t, m)$ and inverse sensor model for position $p(x_t |z_t,m_{t-1})$. From this answer, it seems like one way for ...
• 121
1 vote
1 answer
211 views

### Do we need a backend graph optimizer for OctoMap?

As far as I know, OctoMap or any other grid occupancy maps are only for mapping. How do they handle a loop closure problem? The first method came to my mind is optimizing a pose graph in the backend ...
• 1,375
3 votes
2 answers
1k views

### How to evaluate 3D Occupancy grid maps

I would like to know how to go about evaluating 3D occupancy grid maps. I have a SLAM system that produces a 3D OGM (in .bt format using octomap/octovis) I also have a ground truth OGM in same .bt ...
• 31
2 votes
2 answers
825 views

### How does fast slam creates grid maps?

I've implemented fast slam using landmark detection and the map stored is a feature map, made of landmarks positions. I would like to create a grid map, and my questions are about how does the robot ...
4 votes
1 answer
288 views

### In order to integrate MCL and Occupancy Grid to implement Grid-based FastSLAM, do you have to record all data?

It's unclear as to how one goes about integrating Occupancy Grid mapping and Monte Carlo localization to implement SLAM. Assuming Mapping is one process, Localization is another process, and some ...
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1 vote
1 answer
156 views

### Grid mapping probability calculation algorithmic complexity

I have stumbled upon an equation (http://i.stack.imgur.com/hv64E.png), where the probability of an occupancy grid map cell is calculated. My teacher insists that it's possible to approximate the ...
1 vote
3 answers
567 views

### Can mapping be done in real life applications without also solving the localization problem at the same time (i.e. SLAM)?

I know that Occupancy Grid Mapping requires the assumption that the robots' pose is always known when generating a map. However, I also know that in reality, position and orientation usually treated ...
• 1,238
1 vote
1 answer
119 views

### Finding changes in environment using 2d laser

I have known map of the environment (2d occupancy grid map). I am trying to find if anything changed in environment using 2d laser while navigating by using maximum likelihood of laser with known map. ...
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