convert_octree: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/convert_octree - from package: octomap

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/convert_octree - from package: octomap-tools

You may install the required package with command apt-get install {package}

Error in other languages:
convert_octree: bevel nie gevind nie
convert_octree: comandă negăsită
convert_octree: comando não encontrado
convert_octree: commande introuvable
convert_octree: command not found
convert_octree: käsku ei ole
convert_octree: không tìm thấy lệnh
convert_octree: komanda nerasta
convert_octree: Kommando nicht gefunden.
convert_octree: kommandot finns inte
convert_octree: komut yok
convert_octree: nie znaleziono polecenia
convert_octree: níor aimsíodh an t-ordú
convert_octree: no se encontró la orden
convert_octree: no s'ha trobat l'ordre
convert_octree: opdracht niet gevonden
convert_octree: parancs nem található
convert_octree: perintah tidak ditemukan
convert_octree: príkaz nenájdený
convert_octree: příkaz nenalezen
convert_octree: команда не найдена
convert_octree: командата не е открита
convert_octree: 命令找不到
convert_octree: コマンドが見つかりません