worldtovoxel: command not found

Have You tried accessing the binary with the full path?

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 Debian possible default full paths are:

/usr/bin/worldtovoxel - from package: minc-tools

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