# Exercise U3-1 too many tables detected

**URL:** <https://get-help.theconstruct.ai/t/exercise-u3-1-too-many-tables-detected/2210>\
**Category:** ROS Perception in 5 Days\
**Created:** [February 7, 2020, 2:07am UTC](https://get-help.theconstruct.ai/t/exercise-u3-1-too-many-tables-detected/2210 "2020-02-07T02:07:01Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![fgenestcvdl](https://get-help.theconstruct.ai/user_avatar/get-help.theconstruct.ai/fgenestcvdl/32/9348_2.png) [@fgenestcvdl](https://get-help.theconstruct.ai/u/fgenestcvdl)\
**Post date:** [February 7, 2020, 2:07am UTC](https://get-help.theconstruct.ai/t/exercise-u3-1-too-many-tables-detected/2210/1 "2020-02-07T02:07:02Z")

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In the exercise 3.1 the number of table detected is changing randomly before a start moving i have table[0] and table[1] and as i move forward once in a while it goes up to 4 tables detected simultaneously.

How do i choose the good one ?

An other question ? are the position in the table\_array relative to the robot camera or to the map origin ?

A solution to this exercise is missing.

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**Author:** ![duckfrost2](https://get-help.theconstruct.ai/user_avatar/get-help.theconstruct.ai/duckfrost2/32/9365_2.png) [@duckfrost2](https://get-help.theconstruct.ai/u/duckfrost2)\
**Post date:** [March 5, 2020, 5:20pm UTC](https://get-help.theconstruct.ai/t/exercise-u3-1-too-many-tables-detected/2210/2 "2020-03-05T17:20:22Z")

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Its true that a solution is not given and we will work on it.

Once that is said, basically the topic published where all the detected tables are placed, is an array of tables, that each one has information about its pose, and therefore we can filter based on the zheight, becuase we want to use one or another table, maybe the closest one.

The frame is : frame\_id: “head\_camera\_rgb\_optical\_frame”

Al the information you can get it by executing these comands and extracting the information you need:

> rosmsg show object\_recognition\_msgs/TableArray

> object\_recognition\_msgs/Table tables  
> std\_msgs/Header header  
> uint32 seq  
> time stamp  
> string frame\_id  
> geometry\_msgs/Pose pose

You can see that its an array that has poses.

And you have to susbcribe to this topic: _/table\_array_

With that all the info you need is there. Hope it helps

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<div class="post-metadata">

**Author:** ![fgenestcvdl](https://get-help.theconstruct.ai/user_avatar/get-help.theconstruct.ai/fgenestcvdl/32/9348_2.png) [@fgenestcvdl](https://get-help.theconstruct.ai/u/fgenestcvdl)\
**Post date:** [March 5, 2020, 10:47pm UTC](https://get-help.theconstruct.ai/t/exercise-u3-1-too-many-tables-detected/2210/3 "2020-03-05T22:47:27Z")

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Thanks for the reply

I will try to find a way to sort the tables.

When you will have a solution to the exercice please let me know.