2. Revenue: Schedule of geographical revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Application total
Product Application	$ 7,165	$ 7,581
Transferred at Point in Time
Product Application	816	481
Transferred over Time
Product Application	6,349	7,100
Audio-Visual Systems
Product Application	4,547	3,997
Domes
Product Application	1,295	2,702
Show Content
Product Application	771	326
Maintenance and Service
Product Application	552	556
Planetarium Theaters | Application total
Product Application	6,520	6,243
Planetarium Theaters | Transferred at Point in Time
Product Application	816	481
Planetarium Theaters | Transferred over Time
Product Application	5,704	5,762
Planetarium Theaters | Audio-Visual Systems
Product Application	4,396	3,986
Planetarium Theaters | Domes
Product Application	801	1,375
Planetarium Theaters | Show Content
Product Application	771	326
Planetarium Theaters | Maintenance and Service
Product Application	552	556
Other Visitor Attractions | Application total
Product Application	569	978
Other Visitor Attractions | Transferred at Point in Time
Product Application	0	0
Other Visitor Attractions | Transferred over Time
Product Application	569	978
Other Visitor Attractions | Audio-Visual Systems
Product Application	151	11
Other Visitor Attractions | Domes
Product Application	418	967
Other Visitor Attractions | Show Content
Product Application	0	0
Other Visitor Attractions | Maintenance and Service
Product Application	0	0
Architectural Treatments | Application total
Product Application	76	360
Architectural Treatments | Transferred at Point in Time
Product Application	0	0
Architectural Treatments | Transferred over Time
Product Application	76	360
Architectural Treatments | Audio-Visual Systems
Product Application	0	0
Architectural Treatments | Domes
Product Application	76	360
Architectural Treatments | Show Content
Product Application	0	0
Architectural Treatments | Maintenance and Service
Product Application	0	0
North America
Product Application	4,470	3,613
North America | Planetarium Theaters
Product Application	4,179	3,133
North America | Other Visitor Attractions
Product Application	215	120
North America | Architectural Treatments
Product Application	76	360
Europe
Product Application	1,689	344
Europe | Planetarium Theaters
Product Application	1,373	333
Europe | Other Visitor Attractions
Product Application	316	11
Europe | Architectural Treatments
Product Application	0	0
Asia
Product Application	523	3,303
Asia | Planetarium Theaters
Product Application	485	2,456
Asia | Other Visitor Attractions
Product Application	38	847
Asia | Architectural Treatments
Product Application	0	0
Other
Product Application	483	321
Other | Planetarium Theaters
Product Application	483	321
Other | Other Visitor Attractions
Product Application	0	0
Other | Architectural Treatments
Product Application	$ 0	$ 0