Drag the file you have exported from Autocad on a photoshop artboard 3500px x 1918px.
Duplicate the layer and fill the sectioned walls with black paint bucket tool.
Drag the image of a texture for the internal walls of the building. Select empty spaces of the section through Magic Wand tool, right click on the texture and create new layer via copy.
Create a new layer on Multiply mode to draw the shadows on corners and on dark areas of the interior.
Create a new layer to add natural light.
Select a soft round brush tool, 40% of opacity and Muliply mode to lighting up certain areas.
Add lines with Outer Glow effect to simulate tube shaped lighting fixtures to be placed on ceiling. The Outer Glow effect will intensify the light close to the light source.
Define the zone to light up with Lasso tool. Use a white and soft Brush tool to create the effect of natural light coming through the glazed facade.
Add Gaussian Blur filter to soften the contour between shade and highlights.
Drag a new image for the railing’s panels in Corten steel. Scale and duplicate the image to cover all the railing surface. Merge layers to reduce the file’s weight. Select the railing with the Magic Wand and choose New Layer via Cut of the texture image.
Add lighting on steps with a smaller brush.
Insert an image that will go on background.
Duplicate the image to cover all the length of the paper and use rubber tool to hide the overlap of the two images.
On the light layer delete traces of the brush tool outside the building section.
Put the part of the image below the ground line and reduce the opacity to emphasize the section.
Create a glazed corner that cuts through the section with rectangular selection.
Draw a rectangle with black stroke and no fill. To create the shadow add the “drop Shadow” effect.
Go back to the Light layer, cut the shadow of the platform roof.
On a new folder, insert the new layers to create silhouette of people.
Add elements and people to enrich the drawing. In that case, changing hue and saturation, I have used a person to create a modern statue.
With rectangle and line tool draw the lamps the would goon the walls.
Use Flip Horizontal to flip the spotlight on the other side of the panel. Use Lasso tool and brush tool to draw the light coming out of the spotlight.
For the bar zone, drag the image of suspended light that have been traced. With soft brush tool add some diffuse light around bulbs.
Insert another image for the entrance lighting.
Use Overlay mode and erase the unnecessary with rubber tool.
With pen tool draw the external pavement. Use a pattern to fill the shape and simulate stone effect. Overlap black transparent shapes to create shades on the perimeter of the pavement.
Here you can see the difference between before and after.