Of the 82,748 files recovered from Wittig's electronic devices, 1071 were deemed to be child-exploitation material and another 10 were objectionable material involving adults.
This included 201 computer-generated images and 207 videos.
Due to the nature of the images, police viewed only 30 to protect the investigating officer from the harmful effects of seeing this type of material, the Crown summary said.
On a USB memory stick found at his home, police found 25 videos of sexual activity involving adults and children, including a baby and children 1 to 7 years of age.
Documents found also contained young girls in sexually explicit poses.
Records of Skype conversations in 2017 between Wittig and an unidentified person also revealed the pair shared sexually graphic videos.
Wittig's crimes also included engaging in money laundering and 17 charges of entering into a deal involving a person aged under 18 for the purpose of sexual exploitation.
He also admitted 14 charges of being a party to sexual violation outside of New Zealand and four charges of being a party to indecent assault on a child outside NZ.
Police uncovered Wittig's online profile user name and evidence that he had paid to have child sexual abuse sex shows livestreamed to him from the Philippines.
He had engaged in chat conversations with a Philippines-based offender to facilitate the making of the shows.
Wittig specified the content of the images and videos he wanted to see and stated his preference that the victims should be "as young as possible ... like a baby girl."
He made 48 online payments totalling $1811.34 to a Philippines account holder.
During the investigation into Wittig, police discovered a hydroponic cannabis cultivation system in a crawl-space dug underneath his house.
It contained 42 small plants and heavy budded "mother-plant" growing under 8 energy-saving lights controlled by a digital timer.
About 400 cannabis seeds were also found and inside the washhouse were various glass jars containing about 60 milligrams of cannabis oil.
Wittig admitted selling about 40 cannabis tinnies a week for about two months.
He was also sentenced on charges of cannabis cultivation, selling cannabis and producing cannabis oil, plus a charge of attempting to pervert the course of justice.
Crown solicitor Anna Pollett told Judge Thomas Ingram that Wittig would need a long period of "intensive therapy" because he was assessed at high risk of re-offending.
Lawyer Craig Horsley said his client had shown remorse and acknowledged that serious harm was caused to his victims both in New Zealand and the Philippines.
Judge Ingram said, unfortunately, child pornographic exploitation prosecution cases were becoming an "almost daily event' in our courts and a deterrent sentence was required.
The judge said this was " very serious' offending' and that he was satisfied a jail term of 13 years was appropriate.
Hunting down sex criminals
The case of Steven James Wittig is an example of how offenders are being tracked around the globe.
That's the warning from Jared Mullen from the Department of Internal Affairs, whose job is to stamp out this type of criminal behaviour.
"It results in a visual recording of serious physical and sexual assaults against children that are forever captured and circulated on the internet.
"This material not only captures the worst moments in a child's life but also captures the depiction of a crime scene. This is why we do not use the term child pornography.
"This is not pornography, there is no consent. The correct terminology is child sexual exploitation material."
Mullen said the prevalence of this type of offending was now well-established in New Zealand and internationally.
Victims were often driven into exploitation through poverty "and in some cases, family members facilitate the abuse of children by overseas offenders who direct the abuse from the perceived safety of their homes".
In New Zealand police, Customs and Internal Affairs worked closely together to investigate the possession, production and distribution of child abuse material, he said.
Internal Affairs also worked with government and non-government agencies to provide prevention messages and advice to children, parents and caregivers so that children were less likely to become victims of online offenders, he said.
