# Create DSM and merge several subprojects **URL:** \ **Category:** PIX4Dmapper Questions/Troubleshooting\ **Created:** [March 27, 2018, 4:19pm UTC](https://community.pix4d.com/t/create-dsm-and-merge-several-subprojects/6280 "2018-03-27T16:19:15Z")\ **Posts on this page:** 1\ **Showing post:** 4
**Author:** ![Rhea\_Garratt](https://sea2.discourse-cdn.com/pix4d/user_avatar/community.pix4d.com/rhea_garratt/32/403_2.png) [@Rhea\_Garratt](https://community.pix4d.com/u/Rhea_Garratt)\ **Post date:** [April 5, 2018, 11:57am UTC](https://community.pix4d.com/t/create-dsm-and-merge-several-subprojects/6280/4 "2018-04-05T11:57:37Z")
Hi, You are welcome 🙂 You can find our minimum and recommended system requirements **[here](https://support.pix4d.com/hc/en-us/articles/202557289)**. To process over 10’000 images, you should definitely have a very good computer with more RAM than 32 GB. Users and one of my colleagues raise some good points, regarding hardware, processing time and use of the outputs in third-party software in the following community topic: **[Experience with large datasets?](https://community.pix4d.com/t/4086)**. I recommend you read the thread and comment on it to make it active again. If what you are interested in are the DTM and the orthomosaic, you could consider generating these outputs for each sub-project, then merging them in a third-party software (for example QGIS). To make sure the edges of the maps (DTM and orthomosaic) for each subproject are contiguous (no overlap and no gaps), you should use a **[processing area](https://support.pix4d.com/hc/en-us/articles/202560179)** in each subproject. I recommend you create contiguous areas in a GIS software (for example QGIS), export them in the shapefile format and import them in your subprojects. The workflow for each subproject would be the following: 1. Process step 1. 2. Add a processing area. 3. Process step 2. 4. Edit the point cloud. 5. Generate the DTM and/or the orthomosaic. Then, you could merge the tiles in a third-party software (for example QGIS). I hope this helps! --- _[View the full topic](https://community.pix4d.com/t/create-dsm-and-merge-several-subprojects/6280)._